JP2003202436A - Wavelength demultiplexer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce splice loss between an input slab and a channel waveguide and to reduce loss by suppressing excitation of higher modes as to a wavelength demultiplexer which is suitably used for an array waveguide diffraction grating type wavelength multiplexer/demultiplexer used for wavelength division multiplex communications. <P>SOLUTION: On a substrate are fored, a 1st waveguide 1 which propagates wavelength division multiplex light beams of a plurality of channels, a 1st slab 2 which diffuses the light beam from the 1st waveguide 1, a plurality of channel waveguides 3 which have their lengths set so as to have specified waveguide length differences and receive and propagate distributed light from the 1st slab 2, a 2nd slab 4 which receives distributed light beams from the channel waveguides 3 and converge wavelength demultiplexed light beams, and a 2nd waveguide 5 which propagates light from the 2nd slab 4. The number of connection spots where the channel waveguides 3 and 1st slab 2 are optically connected is made greater than connection spots where the channel waveguides 3 and the 2nd slab 4 are connected. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arrayed waveguide diffraction grating (AWG; Arrayed) used particularly for wavelength division multiplexing communication.
The present invention relates to a wavelength demultiplexer suitable for use in a Waveguide Grating type wavelength multiplexer / demultiplexer.

[0002]

2. Description of the Related Art FIG. 28 is a block diagram showing the structure of a conventional AWG type wavelength multiplexer / demultiplexer.
ngth Division Multiplexing Apparatus) and Wavelength Division Demultiplexing Apparat
us). In the following description, the wavelength multiplexer / demultiplexer will be referred to as MUX / DEMU.
The symbol "X" is used to mean a wavelength multiplexer or wavelength demultiplexer unless otherwise specified. Also, this M
Focusing mainly on the demultiplexing function of the multiplexing and demultiplexing functions of the UX / DEMUX, a case of functioning as a wavelength demultiplexing device will be described. The multiplexing function of the MUX / DEMUX is opposite to the case where the light input / output direction is the demultiplexing function.

The MUX / DEMUX 10 shown in FIG.
Reference numeral 6 denotes a single input waveguide 101, an input slab 102, a channel waveguide 103, and an output slab 10 on a substrate 100.
4 and n output waveguides 105 are provided in the surrounding region 100.
The refractive index is relatively larger than that of A. In the following, a portion made of a material having a relatively high refractive index as compared with the region 100A is referred to as a "core".
A portion made of a material having a relatively low refractive index surrounding the core, such as the region 100A, may be referred to as a "clad". The above-mentioned input waveguide 1, input slab 2,
The channel waveguide 3, the output slab 4, and the output waveguide 5 correspond to the core, and the surrounding region 100A corresponds to the clad.

Further, the MUX / DEMU shown in FIG.
In X106, when the light multiplexed in the wavelength region is input to the input waveguide 101 of this MUX / DEMUX 106, channels # 1 to # of the output waveguide 105 are input.
Light separated for each wavelength is output from n. On the other hand, each channel # 1 to # 1 of the output waveguide 105
When light of a plurality of different wavelengths is input to the channel #n, all the light is bundled from the input waveguide 101, and the light multiplexed in the wavelength region is output.

The structure of the MUX / DEMUX 106 will be described below with reference to a conventional spectroscope (spectroscope or monochro-meter).
This will be described in comparison with the configuration of FIG. This MUX / DEMUX1
The function of 06 is, for example, A shown in FIG. 28 and FIG.
In addition to the WG type, it is realized by a spectroscope type device shown in FIG. 29B and other devices. FIG. 29B is a diagram showing a configuration example of a conventional spectroscopic device. The one shown in FIG. 29B is a bulk diffraction grating type, and it is generally difficult to reduce the pitch of the diffraction grating. . On the contrary,
The AWG type does not need the pitch, and only needs to design the difference in the lengths of the waveguides forming the AWG.

On the other hand, FIG. 29 (a) shows an AWG type MUX /
It is a schematic diagram which shows the core pattern of the waveguide of DEMUX106, paying attention to the core part in MUX / DEMUX106. The MUX / shown in FIG.
The constituent members (components, elements or parts) 101 to 105 of the DEMUX 106 correspond to the constituent members of the spectroscopic device.

FIG. 29 (c) is a diagram showing the correspondence between the wavelength multiplexing / demultiplexing device constructed by using a waveguide and the components of the conventional spectroscopic device. This correspondence will be described with reference to FIG. A spectroscopic device (diffraction grating type spectroscope) 110 shown in FIG. 29B includes an input optical fiber 111, an input collimating lens 112, a condensing lens 114, and n output lights in addition to the diffraction grating 113 having projections and depressions. It is configured with a fiber 115.

This MUX / DEMUX 106 (see FIG. 29)
The input waveguide 101 constituting (a) is one for diffusing and outputting the wavelength-multiplexed laser light to be demultiplexed to the input slab 102 at the subsequent stage, and FIG.
As shown in (3), the input optical fiber 111 of the spectroscopic device 110 is functionally corresponding in that it has a role of an entrance slit that spreads light.

Similarly, the input slab 102 is the input waveguide 1
The light incident on 01 is diffused in the input slab 102 and coupled to the channel waveguide 103 in the subsequent stage.
10 corresponds to the function of the input collimator lens 112 (function of aligning the incident light power from the input optical fiber 111 and irradiating the diffraction grating 113 in the subsequent stage). The channel waveguide 103 corresponding to the diffraction grating 113 of the spectroscopic device 110 forms a phase difference so that light is deflected at a specific angle as described later, and the output slab 104 corresponding to the condenser lens 114 is , The output waveguide 105 corresponding to the output optical fiber 115 converges the diffracted light emitted from the channel waveguide.
Part of the spectrum of the light emitted from No. 4 is cut out.

Here, regarding the length of the channel waveguide 103, M shown in FIG. 28 and FIG.
The channel waveguide located on the lowermost side of the UX / DEMUX 106 is formed so as to have the shortest length, and the length becomes longer toward the upper side. Here, the difference in length between adjacent channel waveguides is constant. This channel waveguide plays an important role in wavelength division (splitting of light by wavelength) or wavelength division multiplexing. Hereinafter, the channel waveguide 103
The action of will be explained.

FIGS. 30 (a) and 30 (b) are respectively shown in FIGS.
It is a figure which shows three adjacent channel waveguides among the some channel waveguides 103 of MUX / DEMUX106 shown in FIG.29 (a). These FIG. 30 (a),
Each of the channel waveguides 131, 132, and 133 shown in (b) has a “peak” position (black dot) and a “valley” position (white dot) of the light wave. here,
The light wave propagating through the channel waveguides 131 to 133 is cos.
When expressed by (α) (α represents the phase), the “mountain” is the phase α.
Represents the position where 2 × n × π, and the “valley” is the phase α
Represents the position where (2n + 1) × π. Note that n and π represent positive integers and pi, respectively.

Therefore, in each of FIGS. 30 (a) and 30 (b), the length between two adjacent "mountains" is equal to the wavelength of the light wave propagating through the channel waveguides 131-133. That is, the light wavelengths shown in FIGS. 30A and 30B are equal to λ ₀ and λ ₁ . FIG. 30A shows the phase of light when light having a wavelength corresponding to the central wavelength in the optical wavelength arrangement used for wavelength division multiplexing is incident. The length of the channel waveguide 103 is designed so that an integer number of light beams having a central wavelength λ ₀ can be contained in the wavelength-division-multiplexed light beams. Specifically, in the case of FIG. 30A, the shortest waveguide 131 has a center wavelength λ ₀ of 9 waves, the central waveguide 132 has 10 waves, and the longest waveguide 133 has 11 waves. Is designed.

For example, as shown in FIG. 31 to be described later, when channels # 1 to # 11 are set in order from the short wavelength band, the wavelength of the light set to channel # 6 is the above-mentioned center. It corresponds to the wavelength λ ₀ . That is, FIG.
As shown in (a), the light wave having the center wavelength component output from each of the waveguides 131 to 133 is output by the output slab 104.
The phases are aligned at the position of the slab boundary line 142 with. In other words, the equiphase surface p1 of the light wave of wavelength λ ₀ output from the channel waveguide 103 is
31-133 are perpendicular to the three waveguides 131-13
The light output from the optical waveguide 3 is diffracted in the correct horizontal direction d1 with respect to the output azimuth of the waveguides 131 to 133.

However, as shown in FIG. 30B, the phase of the light wave having the wavelength λ ₁ which is Δλ shorter than the center wavelength component is not aligned at the position of the slab boundary line 142 with the output slab 104 and is adjacent to each other. Waveguide 131
Thus, the phases are aligned at the positions shifted by the unit of Δλ between 133 and 133. In other words, the equiphase surface p2 of the light wave of wavelength λ ₁ is not perpendicular to the waveguides 131 to 133, and the light output from the waveguides 131 to 133 is also diffracted in the upper direction d2 in the figure.

In the case of a light wave longer by Δλ than the central wavelength λ ₀ , it is diffracted downward in the figure according to the same principle as the above case. Therefore, in the channel waveguide 103, since the diffraction direction (diffraction angle) is determined according to the value of the wavelength-multiplexed light wavelength, the wavelength-multiplexed light can be dispersed. Further, the output slab 104 collects the light diffracted in each channel waveguide 103 in a predetermined diffraction direction for each wavelength and is dispersed, and supplies it to the output waveguide 105 of the corresponding channel.

On the contrary, light output to channels # 1 to #n (for example, ch # 1 output to ch # 11 output shown in FIG. 31)
Light of a specific wavelength corresponding to (in WDM communication, usually,
Light with a spectrum narrower than the bandwidth of the MUX / DEMUX 106 is used. ) Is input to the output waveguide 105 (see FIG. 28) that outputs channel # 1 to channel #n, all the light is bundled and input waveguide 101 (see FIG. 2).
8)).

FIG. 31 shows the above-mentioned FIG. 28 and FIG. 29 (a).
FIG. 9 is a diagram showing an example of the spectral characteristics and insertion loss of the MUX / DEMUX 106 shown in FIG. 1, but 11 channels (channel (ch) # 1 to channel # 1) with respect to the input waveguide 101.
When the 1) wavelength-multiplexed light is input, the output waveguide 105 outputs light with the intensity as illustrated in the channels # 1 to # 11 of FIG.

The basic configuration and operation of an AWG, which is a device related to the present invention, is described in, for example, "IEEE JOURNAL OF SEL".
ECTED TOPICS IN QUANTUM ELECTRONICS. VOL. 2 No. 2.
pp.236-250 (1996) "and Kenji Kawano," Fundamentals and Applications of Optically Coupled Systems for Optical Devices, "Hyundai Kogakusha (1991), 31.
Page, formula (3.1-7) and the like. The wavelength demultiplexing device according to the present invention is the same as the one described in the above-mentioned reference with respect to the configuration, function, and operation other than the characteristic parts of the present invention.

The insertion loss of the MUX / DEMUX 106 is the loss at which the transmittance is maximum for each of the channels # 1 to #n of the output waveguide 105, in other words, the loss at the wavelength where the loss is the smallest with respect to the input light. That is, it is different for each channel. For example, as shown in FIG. 31, MU
The insertion loss of the X / DEMUX 106 depends on the output channel (#
1 to #n).

The factors causing the insertion loss as shown in FIG. 31 are mainly the input slab 102 and the channel waveguide 10.
3 (refer to the slab boundary line 122 shown in FIG. 30; hereinafter referred to as a connection part) and the channel waveguide 10.
3 and the output slab 104 (see the slab boundary line 142 shown in FIG. 30). 32 (a) to 32
FIG. 32C is a diagram for explaining the factors causing the insertion loss in the connection portion between the input slab 102 and the channel waveguide 103, and FIG. 32A is the MUX / DEM.
32 (b) is an enlarged view of the input slab 102, showing the main part of the UX 106, and FIG. 32 (c).
Is an enlarged view of the connection between the input slab 102 and the channel waveguide 103.

Here, as shown in FIG. 32 (c), focusing on the slab boundary line 122 which is the connecting portion between the input slab 102 and the channel waveguide 103, the input slab 1
Of the incident light 8 traveling from 02 to the channel waveguide 103, the light 85 propagating through the channel waveguide 103 is effective, but the light reaching the gap portion 123 is scattered and becomes invalid light 86, which causes loss. Become.

As a first method for reducing the insertion loss as described above, the MUX / DEMUX shown in FIG. 28 is used.
As an input slab applied to 106, it is conceivable to configure an input slab 102-1 as shown in FIG. The input slab 102-1 shown in FIG.
By reducing the channel waveguide spacing dc,
The connection loss of the channel waveguide 103 is reduced.

That is, as illustrated in FIG. 33B, the width w of the channel waveguide 103, the focal length f (the distance from the incident light diffusion center 21 to the incident position of the channel waveguide 103) and the number of channel waveguides. If the channel waveguide spacing dc is reduced under the condition that the above is constant, the connection loss of the channel waveguide can be reduced.

[0024]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention (1-1)
The problem is explained in (1-3). (1-1) However, the MUX / DEM shown in FIG.
In the UX 106, since the shape of the connecting portion between the input slab 102 and the channel waveguide 103 and the shape of the connecting portion between the output slab 104 and the channel waveguide 103 are symmetrical, the channel waveguide 10 on the input slab 102 side is formed.
3 is narrowed (see FIG. 33A), the channel waveguide 103 on the output slab 104 side is reduced.
Interval (not shown) is also reduced. In that case, in the vicinity of the output slab 104 described next, the channel waveguide 1
The light propagating through 03 is coupled with each other and interferes with each other.

That is, the optical waveguide has a property that the light propagating through the waveguide is coupled when the plurality of the waveguides come close to each other and the distance between them becomes small. Therefore, the channel waveguide 1
When the interval of 03 is made small, in the vicinity of the output slab 104, the lights propagating in the channel waveguide 103 are mutually coupled and interfere with each other. In addition, as shown in FIG.
The X / DEMUX 106 includes channel waveguides 131 to 13
At the output aperture 142 of No. 3, the light propagating through the channel waveguides 131 to 133 has a phase difference, thereby functioning as a wavelength division multiplexer.

Here, if the spacing between the channel waveguides 131 to 133 near the output slab 104 is narrowed and the light propagating through these channel waveguides 131 to 133 is coupled, the phase is changed and the wavelength demultiplexing function is achieved. Depress
To do. Therefore, the MUX / DEMUX1 illustrated in FIG.
Regarding No. 06, as a means for reducing the insertion loss, the spacing between the connection portions of the input slab 102 and the channel waveguide 103 (the channel waveguide spacing dc shown in FIGS. 32 (c) and 33 (a), respectively) and the output slab. There is a problem in that it is not possible to narrow the distance (not shown) between the connecting portions of the channel 104 and the channel waveguide 103.

(1-2) Next, as a second method for reducing the connection (scattering) loss between the input slab 102 and the output slab 104 and the channel waveguide 3 shown in FIG. 28,
The channel waveguide 103-1 may be configured as shown in FIG. 34 (a), for example. That is, this FIG.
As shown in FIG. 4 (a), the input side connection portion 1 where the channel waveguide 103-1 is connected to the input slab 102.
At 07, a tapered connection branch 162 is formed whose width becomes narrower as it goes away from the input slab 102 side (hereinafter, a pattern in which the waveguide width changes narrowly like the tapered connection branch 162 is called a tapered shape. To).

In the method shown in FIG. 34 (a),
For example, as shown in FIG. 34B, the tapered connecting branch 16
As the width of the portion where 2 is connected to the input slab 102 becomes wider, the scattering loss of the input side connecting portion 107 decreases. However, in the MUX / DEMUX 106 to which the channel waveguide 103-1 having the tapered connecting branch 162 as shown in FIG. 34 (a) is applied, the tapered shape formed between the input slab and the channel waveguide is used. Connection branch 162
In the above, the higher-order mode light is excited as described below, and the excited higher-order mode light is radiated to the outside of the channel waveguide (core), causing a loss.

FIG. 35 is a diagram showing how high-order mode light is excited in the channel waveguide 103-1 and radiated to the outside of the core. Incident light 8 from the input waveguide 101 shown in FIG. 35 is the tapered portion 162 of the channel waveguide 103-1.
When coupled to, second-order mode light 82 is excited in addition to 0-th order mode light 80a. Here, the 0th-order mode light 80a becomes 0th-order mode light 80b when it propagates through the tapered portion 162 and reaches a narrow portion. The secondary mode light 82 (refer to the part labeled P22 in FIG. 35) is emitted to the outside of the channel waveguide 103-1 while propagating through the tapered portion 162, and becomes a loss.

Specifically, the light incident on the tapered connection branch 162 from the input slab 102 has two or more intensity peaks in the tapered connection branch 162 formed as the core. While propagating, a part of light (corresponding to higher-order mode light) is radiated to the outside of the channel waveguide (core) 103-1 in the process of changing the number of peaks, resulting in a loss.

Therefore, also in the MUX / DEMUX to which the channel waveguide 103-1 shown in FIG. 34 (a) is applied, loss occurs because the higher mode light emitted outside the channel waveguide 103-1 is radiated. There is a problem. (1-3) Furthermore, in (1-1) above, at the output end of the channel waveguide 103, coupling of light propagating through the channel waveguide 103 is prevented, and this is the origin of the wavelength multiplexing / demultiplexing action. Phase difference (for example, channel waveguide 1 of FIG. 30B)
It is necessary to maintain the phase difference of the light propagating through 03. Therefore, it is required to keep the distance between the channel waveguides 103 on the output slab 104 side wide.

Furthermore, it is necessary to reduce the gap that causes the loss (for example, the gap portion 123 shown in FIG. 32C). Therefore, the space between the channel waveguides 103 on the input slab 102 side (see FIG. 32C and FIG. 33).
It is required to narrow the channel waveguide spacing dc shown in (a). The present invention has been made in view of the above problems, and for example, in a wavelength multiplexing / demultiplexing device in which the shapes of the input slab and the output slab are symmetrical as shown in FIG. 28, in the connection portion of the output slab and the channel waveguide. An object of the present invention is to provide a wavelength demultiplexing device capable of reducing the loss by narrowing the channel waveguide spacing at the connection portion between the input slab and the channel waveguide while keeping the channel waveguide spacing wide.

At the same time, the present invention is a wavelength demultiplexer capable of suppressing the higher-order modes excited in the channel waveguide of the conventional example (for example, FIG. 35) and reducing the loss as described in (1-2) above. The purpose is to provide a device.

[0034]

Therefore, the wavelength demultiplexing device of the present invention is provided with a first waveguide for propagating wavelength-multiplexed light of a plurality of channels on a substrate and an input from the first waveguide. A first slab for diffusing the light, a plurality of channel waveguides whose lengths are sequentially set with a predetermined waveguide length difference, and which propagates the light diffused by the first slab by being distributed and input. Each distributed light propagated in the channel waveguide is input,
A second slab that collects the wavelength-separated light and a second waveguide that propagates the light collected by the second slab are formed, and the channel waveguide and the first slab are formed. It is characterized in that the number of connection points for optically connecting is larger than the number of connection points for connecting the channel waveguide and the second slab.

Further, in the wavelength demultiplexing device of the present invention, the first waveguide, the first slab, the plurality of channel waveguides, the second slab and the second waveguide are formed on the substrate as in the case described above. In addition, a channel waveguide in a vicinity portion optically connected to the first slab has a plurality of branch connection branches for inputting the distributed light from the first slab and the distribution from the branch connection branches. It is characterized by being integrally formed with a merging portion that optically couples light.

In this case, the branch connection branch is constructed to have a width such that the higher-order mode light of the input distributed light is cut off, and the coupling contact at the merging portion is the input. It may be formed so that the high-order mode light of the distributed light is excited. In addition, the branch connecting branch is formed to have a width that narrows in a taper shape as it approaches the first slab from the merging portion side, or narrows in a taper shape as it approaches the first slab from the merging portion side. A narrow width having a width substantially equal to that of the narrowest width of the tapered portion and the first slab and the tapered portion optically connected to each other. You may comprise with a waveguide.

Further, in the wavelength demultiplexing device of the present invention, as in the case described above, the first waveguide, the first slab, the plurality of channel waveguides, the second slab and the second waveguide are formed on the substrate. In addition, a channel waveguide in a vicinity portion optically connected to the first slab is composed of a plurality of primary branch connection branches for inputting the distributed light from the first slab and the primary branch connection branch. A plurality of sets of primary coupling portions each having a primary merging portion optically coupling the distributed light, and a plurality of secondary portions for inputting the distributed light coupled by the primary coupling portions. It is characterized in that it is configured by integrally forming a secondary coupling portion having a branch coupling branch and a secondary merging portion optically coupling the distributed light from the secondary branch coupling branch.

In this case, it is preferable that the primary branch connection branch is configured to have a width such that the higher-order mode light of the input distributed light is cut off, and at the merging portion. The coupling contact is formed to have a width in which the higher-order mode light of the input distributed light can be excited. Further, preferably, the branch connecting branch is formed so as to have a width that narrows in a taper shape as it approaches the first slab from the merging portion side, or tapers as it approaches the first slab from the merging portion side. A tapered portion having a narrower width, the first slab and the tapered portion are optically connected, and the width of the tapered portion is about the same as the narrowest portion and has a substantially constant width. It may be configured with a constant narrow waveguide.

Further, in the wavelength demultiplexing device of the present invention, as in the case described above, the first waveguide, the first slab, the plurality of channel waveguides, the second slab and the second waveguide are formed on the substrate. In addition, the channel waveguide has a width in which the higher-order mode light of the distributed light can be excited at the connection point with the first slab, and has a width that narrows in a taper shape with increasing distance from the first slab. And the island-shaped formation region having a lower refractive index than the channel waveguide is provided so as to partition the channel waveguide in the vicinity optically connected to the first slab into a plurality of regions. It has a feature.

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (A) Description of First Embodiment FIG. 1 is a schematic diagram showing a main part of a MUX / DEMUX 10 to which a wavelength demultiplexing device according to a first embodiment of the present invention is applied, and particularly constitutes the MUX / DEMUX 10. This is illustrated focusing on the pattern of the core in the optical waveguide device. Further, FIG. 2 is shown focusing on the core pattern of the connecting portion of the input slab 2 and the channel waveguide 3 which constitute the MUX / DEMUX 10.

MUX / DEMUX according to the first embodiment
28 is an underclad having a refractive index of about 1.551 and a thickness of about 20 μm, for example, by combining SiO ₂ deposition by a CVD (Chemical Vapor Deposition) method and a photolithography process on a silicon substrate 100 as shown in FIG. Layer, refractive index 1.5588, thickness 7μm
It is formed of a core having a thickness of about 20 μm and a thickness of about 20 μm with a refractive index of about 1.551.

That is, the above MUX / DEMUX 10
The core is formed so that the upper, lower, left, and right sides are surrounded by the underclad or the overclad. As a result, the core is covered with the clad layer having a refractive index relatively smaller than that of the core, so that light can be confined and propagated in the core. Also, MUX / DEM
In the core of the UX 10, as shown in FIG. 1, an input slab for diffusing the light input from the input waveguide (first waveguide) 1 and the input waveguide 1 for propagating the wavelength-multiplexed light of a plurality of channels (First slab) 2, a plurality of channel waveguides 3 whose channel lengths are sequentially set with a predetermined waveguide length difference, diffused in the input waveguides 1 are distributed and input, and propagated to the channel waveguides 3 and 3 Output slab (second slab) 4 for collecting the wavelength-separated light by inputting each of the distributed lights propagated by the output waveguide 5 and the output waveguide 5 for propagating the light condensed by the output slab 4.
The pattern that functions as is integrally formed.

Each element will be described in more detail. The input waveguide 1 guides the light input to the input waveguide 1 from the left side of FIG. 1 and delivers it to the input slab 2 (guide and deliver).
r). The input slab 2 is a substrate (for example, reference numeral 10 in FIG. 28).
The light propagating in the input slab 2 is not confined in the lateral direction but diffuses (diverges). Therefore, the input waveguide 1
The light that has reached the input slab 2 through the light diffuses around the incident light diffusion center 21 and reaches the channel waveguide 3. Here, the shape of the slab boundary line 22 (see FIG. 2) that is the boundary between the input slab 2 and the channel waveguide 3 is an arc having a radius f with the incident light diffusion center 21 as the center. Therefore, the light diffused from the incident light diffusion center 21 shown in FIG. 1 is incident on the plurality of channel waveguides 3 in the same phase.
The channel waveguide 3 is formed such that the difference in length from the adjacent input slab 2 to the output slab 4 is constant.

Due to this difference in length, when the light incident on the channel waveguide 3 passes through the channel waveguide 3 and reaches the output aperture 44 thereof, FIG. The phase difference shown in is generated. Here, the output opening 44 is equal to the connecting portion 44 between the channel waveguide 3 and the output slab 4. Since the channel waveguide 3 has a function of producing this phase difference, the phased array (phas
ed array) is called. Further, the difference in length between the adjacent channel waveguides 3 is designed to be m times the central wavelength λ ₀ . m
Is a positive integer and is the order of the channel waveguide 3.
channel waveguide) or phased array order (or
der of the phased array).

The light that has passed through the channel waveguide 3 and reached the output opening 44 of the channel waveguide 3 has an equal phase plane that differs depending on the wavelength. This equiphase surface is, for example, d1 or d2 shown in FIGS. 30 (a) and 30 (b).
Further, like the input slab 2, the output slab 4 is such that the boundary line 42, which is the slab boundary line of the channel waveguide 3 and the output slab 4, and the output opening 44 are both arranged on an arc having a radius r. Is formed in. Therefore, the light output from the output opening 44 of the channel waveguide 3 to the output slab 4 is converged on the center of an arc having a radius r that determines the arrangement position of the slab boundary line 42 and the output opening 44. Strictly speaking, when the wavelength of the light output from the output opening 44 of the channel waveguide 3 is shorter than the central wavelength, it is relatively converged to the upper side in FIG. When the wavelength of the light output from 44 is longer than the central wavelength, it is converged to the lower side.

Further, the output waveguide 5 is arranged such that one end thereof is located at a position where light of a desired wavelength is converged, and the other is used as an output terminal. An input terminal of an optical fiber or other optical component is usually connected to the output end of the output waveguide 5. Here, the input waveguide 1, the input slab 2, the output slab 4, and the output waveguide 5 are basically those shown in FIG. 28 (reference numerals 101, 102, 1).
04 and 105).

As described above, each channel waveguide 3 has
The lengths are sequentially set so as to have a predetermined waveguide survey between the adjacent channel waveguides, whereby the light propagating in each channel waveguide 3 is specified differently for each wavelength wavelength-multiplexed. The light can be deflected (spectralized) at the angle of and emitted to the output slab 4. Further, the midpoints of the respective channel waveguides 3 are formed with necessary intervals so that the propagating lights do not interfere with each other.

The above-mentioned input waveguide 1 and output waveguide 5
The width (core pattern width) and the intermediate portion of the channel waveguide 3 excluding both ends 6 and 7 can both have a waveguide width (core pattern width) of about 7 μm. Further, the center wavelength λ ₀ is set to 1.552 μm, the order m of the channel waveguide 3 is set to 30, and the channel waveguide 3
The effective refractive index of the above can be set to about 1.552, and the difference in length between the adjacent channel waveguides 3 can be set to about 30 μm.

In addition, the channel waveguide 3 on the output slab 4 side
The end portion 7 is formed to have a shape in which the width becomes narrower as it goes away from the output slab 4 side. Specifically, the spacing dc2 of the channel waveguides 3 in the connection portion of the output slab 4 is 22 μm, the width of the tip of the taper (Wmax in FIG. 1) is 19 μm,
The length of the tapered portion of the channel waveguide 3 is 2.5 mm.
Is.

MUX / DEMUX in the first embodiment
The radius f of the input slab 2 and the output slab 4 of 10 are both about 6.2 mm, and their widths are about 1 mm. That is, the slab boundary line 22, the connecting portion 24, the slab boundary line 42, and the connecting portion 44 all have a radius of 6.
It is arranged on a 2 mm arc. Here, the end portion 6 on the side of the input slab 2 has a configuration that characterizes the present invention as described below.

That is, the connection location where the channel waveguide 3 and the output slab 4 are optically connected (the connection portion 24 between the input slab 2 and the channel waveguide 3) is the above-mentioned channel waveguide 3 and the input slab 2. The number of connection points is larger than the number of connection points. Specifically, as shown in FIG. 3, each channel waveguide 3 in the vicinity portion optically connected to the first slab 2, that is, the end portion 6 of each channel waveguide 3 on the first slab 2 side is , Two branch connection branches 61 for inputting the distributed light from the first slab 2, and a branch connection branch 61.
A merging portion 69 that optically couples the distributed light from the
And are integrally formed.

As a result, the space between the portions where the channel waveguide 3 and the input slab 2 are optically connected (for example, in FIG.
The channel waveguide spacings dc11 and dc12 shown in Fig. 32 can be narrowed, and the gap portion (reference numeral 123 in Fig. 32 (c)).
The loss caused by () is reduced. In this case, the channel waveguide spacing at the connecting portion 24 between the input slab 2 and each channel waveguide 3 (see FIG.
Dc1) in the slab boundary line 22 is about 22 μm, and the distance between the branch connection branches 61 on the slab boundary line 22 (dc11 in FIGS. 1 and 2) is about 11 μm. It is possible to set the waveguide length up to about 5 mm and the tapered waveguide length after merging to about 1 mm.

Two branch connecting branches 6 shown in FIGS. 2 and 3.
1 indicates that the center axis 31 at the end 6 on the input slab 2 side of each channel waveguide 3 passes through the center of the gap G1 sandwiched by the two branch connection branches 61, and its extension is the incident light. It passes through the diffusion center 21. In other words, the central axis 31 of the end 6 of each channel waveguide 3
Are aligned with the optical axis of the incident light.

Furthermore, the width of the above-mentioned two branch connection branches 61 is configured to have a width W2 such that the higher-order mode light of the distributed light input from the input slab 2 is cut off. . Further, the width W1 of the coupling contact in the merging portion 69 is formed so that the higher-order mode light of the input distributed light can be excited. The effect produced by this formation will be described with reference to FIGS. 4A and 4B by comparing the operations of the MUX / DEMUX 10 of the present invention and the conventional MUX / DEMUX.

FIG. 4A is a diagram for explaining the propagation of light in the channel waveguide of the conventional MUX / DEMUX. Here, when the incident light 8 is incident on the tapered connection branch 162, most of the light propagates as the 0th-order mode light 80a, but a part of the light is near the connection portion 24 between the channel waveguide 3 and the input slab 2. It is excited by the secondary mode light 82.
Further, since the channel waveguide 162 becomes narrower toward the right side in FIG. 4A, the secondary mode light 82 is cut off when it travels a predetermined distance. As a result, the secondary mode light 82 is radiated to the outside of the waveguide (core) 162 (see the reference symbol P22 in FIG. 4A) and becomes a loss.

On the other hand, in the channel waveguide 3 shown in FIGS. 1 to 3, the branch connection branch 61 is formed of a waveguide having a narrow width W2 so that higher-order modes are cut off. FIG. 4B shows the MUX / DE in the first embodiment.
It is a schematic diagram for explaining the action and effect of the MUX, but as shown in FIG. 4B, the incident light 8 has a branch connection branch 61.
Is incident on the branch connection branch 61, the 0th-order mode light 80a
There is no loss because only the waves propagate.

The merging portion 69 is formed so as to have a width W1 such that a higher-order mode such as the first-order mode is excited, but one (for example, the upper side in the drawing) branch connecting branch 61.
Since the first-order mode due to the light incident from the other side and the first-order mode due to the light incident from the other branch connection branch 61 (for example, the lower side in the drawing) are canceled, the loss due to the higher-order mode does not occur.

In this case, the branch connection branch 6
The length of the waveguide 1 is about 5 mm, the length of the tapered waveguide after joining at the joining portion 69 is about 1 mm, and the maximum width W1 of the tapered waveguide portion at the joining portion 69 is about 16 μm. can do. With the configuration described above, in the optical multiplexer / demultiplexer 10 according to the first embodiment, when light (wavelength multiplexed light) containing a plurality of wavelength components is input to the input waveguide 1, channels # 1 to channels of the output waveguide 5 are input. In #n, it functions as an optical demultiplexing device that outputs wavelength-demultiplexed (wavelength-separated) light for each channel. On the other hand, the optical multiplexer / demultiplexer 1
0 also functions as a wavelength multiplexer that outputs the wavelength-multiplexed light of each of the channels # 1 to #n input to the output waveguide 5 through the input waveguide 1.

Further, in each channel waveguide 3, as in the case of FIG. 30 described above, distributed light is emitted to the output slab 4 at different emission angles for each wavelength, so that wavelength-multiplexed light is emitted. It is demultiplexed every time. Further, the output slab 4 collimates the demultiplexed light of each wavelength and condenses the light of the same wavelength at the incident point of each output waveguide 5. Thereby, in each output waveguide 5, it is possible to propagate lights having different wavelengths for each channel.

As described above, according to the wavelength demultiplexer according to the first embodiment of the present invention, the distances dc11 and dc12 between the connection points where the channel waveguide 3 and the input slab 2 are optically connected are narrowed. Therefore, the connection loss between the input slab 2 and the channel waveguide 3 can be reduced. Furthermore, in this embodiment, as in the conventional example,
There is no loss due to radiation of higher-order mode light, resulting in low loss.

The branch connection branch 61 may be configured such that the central axis 32a of each branch connection branch 61 is arranged on an extension line from the incident light diffusion center 21, as shown in FIG. By doing so, the loss is further reduced. Further, in the above-described first embodiment, each channel waveguide 3 has two channels.
Although one branch connecting branch 61 and the merging portion 69 are provided, the present invention is not limited to this, and a channel waveguide having two branch connecting branches 61 and two merging portions 69 and a branch connecting branch 61 and A channel waveguide having a configuration not branched by the merging portion 69 may be present in parallel, and even in such a configuration, at least the connection loss between the input slab 2 and the channel waveguide 3 can be reduced.

(B) Description of Second Embodiment FIG. 6 is a schematic diagram showing a main part of a MUX / DEMUX 10-1 functioning as a wavelength demultiplexing device according to the second embodiment of the present invention. , Especially MUX /
It shows focusing on the pattern of the core in the optical waveguide device which comprises DEMUX10-1.

MUX / DEMUX according to the second embodiment
In 10-1 as well, as in the case of the above-described first embodiment, the core is formed so as to be surrounded by underclad or overclad on the upper, lower, left, and right sides so that light can be confined and propagated in the core. There is. In addition, the MUX / DEMUX 10-1 in the second embodiment
Is in the first embodiment described above (see reference numeral 10)
Compared with the above, the configuration of the channel waveguide 3-1 is different, but the other configurations are the same as in the case of the first embodiment described above. That is, in the core, together with the channel waveguide 3-1 having the characteristics peculiar to the second embodiment, the same input waveguide 1, input slab 2, output slab 4, and output waveguide as those in the first embodiment described above are provided. The pattern functioning as 5 is integrally formed.

In addition, the channel waveguide 3-1 according to the second embodiment is a channel waveguide 3-1 in the vicinity where it is optically connected to the input slab 2, that is, the channel waveguide 3-1.
The end 6-1 on the input slab 2 side of the input slab 2
A connecting portion 62a with a taper that widens the connecting portion with and becomes narrower with increasing distance from the input slab 2.
(See FIG. 7). The connection portion of the channel waveguide 3-1 with the input slab 2 is formed to have a width Wmax wider than the minimum width in which the higher-order mode light of the input distributed light is excited.

Further, in the vicinity of the position in each channel waveguide 3-1 having the width in which the higher-order mode light is excited, the channel waveguide 3-1 is surrounded by the formation region of the channel waveguide 3-1 and is closer than the channel waveguide 3-1. An island-shaped formation region 34 (see FIG. 7) having a low refractive index is provided. For example, as shown in FIG. 7, the end portion 6 of the channel waveguide 3-1 also has an end portion 6.
As in the case of -1, the width of the connection with the input slab 2 is set to W
On the other hand, it is formed so as to become narrower in a taper shape with increasing distance from the output slab 4. Further, the island formation region 34 extends from the waveguide position C1 having a width of about the minimum width at which the higher-order mode is excited to the position C2 of the slab boundary line 22 at the end 6-1 of the channel waveguide 3-1. ,
It is formed in an island shape such that the periphery thereof is surrounded by the formation region of the channel waveguide 3-1.

Regarding the width W1 at the waveguide position C1 of the apex portion A of the island-shaped formation region 34, the width W1 is formed in a taper shape of at least about the width (for example, about 16 μm) in which a higher-order mode is excited, and the end portion described above is formed. About the middle part other than 6-1 and 7, a width of about 7 μm and a tapered connecting branch 62a
It can be formed to have a length of about 1.5 mm to 5 mm.

The waveguides 61a-1 and 61a-2 partitioned by the island-shaped formation region 34 have a width such that the higher-order mode (second-order mode) of the input distributed light is cut off. It is configured as a waveguide. And
According to the wavelength demultiplexing device of the second embodiment, the gap between the connecting portions 24 where the channel waveguide 3 and the input slab 2 are optically connected becomes small, so that the gap portion (reference numeral 123 in FIG. 32 (c)). The loss caused by () is reduced. Further, as in the case of the above-described first embodiment, the higher-order mode light is cut off by the two waveguides 61a-1 and 61a-2, and further these two waveguides 61a are cut off.
Waveguide position C1 by the incident light from -1, 61a-2
Since the higher-order mode (first-order mode) excited in (1) is canceled at the waveguide position C1, the loss due to the radiation of the higher-order mode light does not occur and the loss becomes low.

As described above, in the channel waveguide 3-1 shown in FIGS. 6 and 7, the waveguide 61 as a branch connecting branch is used.
Since a-1 and 61a-2 are configured by the waveguide having the narrow width W2 so that the higher-order modes are cut off, FIG.
As shown in (b), the incident light 8 is transmitted through the waveguides 61a-1 and 6a.
1a-2, the waveguides 61a-1 and 61a
At -2, no loss occurs because only the 0th-order mode light 80a propagates.

Incidentally, FIG. 8A shows a conventional MUX / DEM.
It is a figure for demonstrating the propagation of the light in the channel waveguide of UX. With the above configuration, the MUX / DEMU that functions as the wavelength demultiplexing device according to the second embodiment of the present invention.
Also in X10-1, when light including a plurality of wavelength components (wavelength multiplexed light) is input to the input waveguide 1, the wavelengths are demultiplexed for each channel in channels # 1 to #n of the output waveguide 5 ( Outputs light (wavelength separated).

Further, due to the island-shaped forming region 34, the angular pitch of the distributed light incident on the end 6-1 of the channel waveguide 3 on the input slab 2 side (the angle of the distributed light incident on the channel waveguide 3 is Since the space) is narrowed, the waveguide width is set to cut off the higher-order mode light of the distributed light,
The cause of loss such as a gap portion (see reference numeral 123 in FIG. 32C) is reduced.

That is, the distributed light incident on the end 6-1 of each channel waveguide 3 on the input slab 2 side is propagated with the higher-order modes cut off. For the first-order mode, the portion C1 where the waveguides 61a-1 and 61a-2 merge.
Therefore, as a result, only the 0th-order mode light is propagated, and the loss of the distributed light is reduced. As described above, according to the wavelength demultiplexing device according to the second embodiment of the present invention, the gap between the connection points where the channel waveguide 3 and the input slab 2 are optically connected is narrowed. As in the case of the embodiment, the input slab 2 and the channel waveguide 3
The connection loss with can be reduced.

(C) Description of Third Embodiment FIG. 9 is a schematic diagram showing a main part of the MUX / DEMUX 10-2 functioning as the wavelength demultiplexing device according to the third embodiment of the present invention. As in the case of the embodiment, the focus is on the pattern of the core in the optical waveguide device forming the MUX / DEMUX 10-2.

MUX / DEMUX according to the third embodiment
Also in 10-2, as in the case of each of the above-described embodiments,
The core is formed so that the upper, lower, left, and right sides are surrounded by the underclad or the overclad, and the light is confined in the core and can propagate. Also,
The MUX / DEMUX 10-2 in the third embodiment is
The configuration of the channel waveguide 3-2 is different from that in each of the above-described embodiments (see reference numerals 10 and 10-1), but other configurations are the same as those in each of the above-described embodiments. It is the same. That is, in the core, together with the channel waveguide 3-2 having the characteristics peculiar to the third embodiment, the same input waveguide 1, input slab 2, output slab 4, and output waveguide 5 as those in each of the above-described embodiments are provided. The pattern that functions as is integrally formed.

That is, as shown in FIG. 10, the end portion 6-2 of each channel waveguide 3-2 has four primary branch connection branches 611 for inputting the distributed light from the input slab 2.
Two sets of primary coupling sections 610 each having a primary merging section 612 for optically coupling the distributed light from the primary branch connection branch 611 and the distributed light coupled by the primary coupling section 610 Two secondary branch connection branches 621 to be input and the above-mentioned distributed light from the secondary branch connection branches 621 are optically coupled 2
The secondary joining portion 620 including the next joining portion 622 is integrally formed.

That is, MUX / in the third embodiment
In the DEMUX 10-2, one channel waveguide 3-2
Is integrally formed with the input slab 2 and four connection points. In other words, the above-mentioned primary coupling section 610 and secondary coupling section 620 are configured as a coupling waveguide that optically couples and propagates a plurality of distributed lights. The coupling part 610 and the secondary coupling part 620 are tandem-connected in a two-stage tree shape.

Further, 4 in each channel waveguide 3-2
The primary branch connection branch 611 of the book is used for each channel waveguide 3-2.
Of the central axis 31 at the end 6 of the input slab 2 side (see FIG. 10).
(Refer to FIG. 9) passes through the center of the gap portion G2 sandwiched by the two primary branch connection branches 611, and its extension line passes through the incident light diffusion center 21 (see FIG. 9). In other words, the central axis 31 of the end portion 6-2 in each channel waveguide 3-2 coincides with the optical axis of incident light.

In FIG. 10, the primary branch connecting branch 6
The width of 11 is about 7 μm, and the distance d between the primary branch connection branches 611 is d.
c11 can be about 16 μm. That is, in the channel waveguides 3-2 shown in FIGS. 9 and 10, the waveguides 611 and 612 as branch connection branches are configured by waveguides having a constant width of, for example, about 7 μm so that higher-order modes are cut off. Since the incident light is transmitted through the waveguide 611,
When incident on, the waveguide 611 propagates only the 0th-order mode, and no loss occurs.

Similarly, in the secondary branch connection branch 621 of the secondary coupling section 620, the distributed light from the primary coupling section 610 is propagated, but also in the secondary branch connection branch 621, for example, Since the waveguide is composed of a waveguide with a constant width of about 7 μm, only the 0th-order mode propagates. In addition, in the primary merging unit 612 and the secondary merging unit 622, as in the case of the corresponding portion (see the reference numeral 69 in FIGS. 1 to 5) in the above-described first embodiment, each upstream branch connection branch 611, 621. It is formed to have a width capable of canceling out the higher-order mode (first-order mode) excited by the distributed light from.

According to the wavelength demultiplexer according to the third embodiment of the present invention, the gap between the connection portion 24 of the input slab 2 and the channel waveguide 3 can be further reduced, so that the gap portion (reference numeral in FIG. 32 (c)). It is possible to further reduce the loss caused by (see 123). In addition, the output slab 4 and the channel waveguide 3 are more than those in the above-described embodiments.
-2, it is possible to increase the channel waveguide interval at the connection portion 44, and it is possible to further suppress optical interference at the end 7 of the channel waveguide 3-2, and particularly optical interference (coupling).
This is effective in preventing interference (coupling) when using a waveguide having a small difference in refractive index, which is likely to occur.

Furthermore, in the above-described third embodiment,
The end portion 6-2 of the channel waveguide 3-2 is connected to the primary coupling portion 61.
0 and the secondary coupling section 620 are tandemly connected in a two-stage tree shape, but the present invention is not limited to this, and the above-mentioned primary coupling sections 610 and 2 are used as coupling waveguides. By using the same configuration as the configuration of the next coupling unit 620, tandem connection may be performed so as to form a tree shape having more than two stages.

Further, in the MUX / DEMUX 10-2 functioning as the wavelength demultiplexing device according to the above-mentioned third embodiment, for example, as shown in FIG. 11, each primary branch connection branch 611 has its central axis 32c. It can also be formed so as to coincide with the optical axis from the incident light diffusion center 21, and such a structure has the same advantages as the case of FIG. 11 described above.

(D) Description of Fourth Embodiment FIGS. 12 to 14 are views showing a fourth embodiment of the present invention, and FIG. 12 functions as a wavelength demultiplexing device according to the fourth embodiment of the present invention. It is a schematic diagram which shows the principal part of MUX / DEMUX10-3, and is what pays attention to the pattern of the core in the optical waveguide device which comprises MUX / DEMUX10-3 similarly to the case of each embodiment mentioned above. is there. 13 is an enlarged schematic view showing a part of the input waveguide 1, the input slab 2 and the channel waveguide 3-3, and FIG. 14 is one channel waveguide 3-3 on the input slab 2 side. It is a schematic diagram which shows the edge part 6-3.

MUX / DEMUX according to the fourth embodiment
Also in 10-3, as in the case of each of the above-described embodiments,
The core is formed so that the upper, lower, left, and right sides are surrounded by the underclad or the overclad, and light is confined in the core and can propagate. Further, the MUX / DEMUX 10-3 according to the fourth embodiment is different from the above-described first embodiment (see reference numeral 10) in the configuration of the channel waveguide 3-3, but other configurations. Is the same as in each of the above-described embodiments. That is, in the core, together with the channel waveguides 3-3 having the characteristics peculiar to the fourth embodiment, the input waveguide 1, the input slab 2, and the input waveguide 1, which are the same as those in the above-mentioned respective embodiments,
Patterns that function as the output slab 4 and the output waveguide 5 are integrally formed. Note that, in FIGS. 12 to 14, the same reference numerals as those in the drawings showing the above-described respective embodiments indicate almost the same parts.

Further, the channel waveguide 3-3 according to the fourth embodiment is a channel waveguide 3-3 in the vicinity where it is optically connected to the input slab 2, that is, the channel waveguide 3-3 on the input slab 2 side. The end 6-3 of 3 has a characteristic core pattern. That is, MUX / of the fourth embodiment
As shown in FIG. 14, the end portion 6-3 of the channel waveguide 3-3 of the DEMUX 10-3 (see FIG. 12 or FIG. 13) has a narrow width W _p at the connection portion 24 with the input slab 2. And has a taper portion 65p that spreads to W ₀ with increasing distance from the input slab 2. Here, for example, if W ₀ is 7 μm and W _p is 2 μm, the connection loss between the input slab 2 and the channel waveguide 3 can be reduced as compared with the case of the first embodiment or the second embodiment.

Here, each of the two branch connection branches 65 has a taper portion 65p having a pattern in which the width becomes narrower as it approaches the input slab 2. In other words, the channel waveguide 3 provided with the two branch connecting branches 65 having the tapered portion 65p and the merging portion 69 at the end portion 6-3.
3 is integrally formed with the input slab 2 to optically connect the input slab 2 and the channel waveguide 3-3.

The branch connection branches 65 are shown in FIG.
As shown in, the central axis 33b at the end 6-3 of each channel waveguide 3-3 passes through the center of the gap portion G1 sandwiched by the two branch connection branches 65, and its extension line is incident. It passes through the light diffusion center 21. Next, in the MUX / DEMUX of the fourth embodiment, the reason why the connection loss between the input slab 2 and the channel waveguide 3 is reduced will be described by comparing FIG. 15 (a) and FIG. 15 (b).

FIG. 15A shows the MU in the fourth embodiment.
It is a figure for demonstrating operation | movement of the input side connection part 6-3 of X / DEMUX10-3 (refer FIG. 12), FIG.15 (b)
Is a MUX / DEMUX 10 (FIG. 1) in the first embodiment.
FIG. 7 is a diagram for explaining the operation of the input side connection unit 6 (see FIG. 4). According to FIG. 15B, since the core width of the branch connecting branch 61 is constant at 7 μm, the tip portion D of the branch connecting branch 61 is
The electric field strength distribution 81 of 1 is the same as the electric field strength distribution 84a of the portion D2 of the branch connection branch 61. At this time, the coupling efficiency between the input slab 2 and the channel waveguide 3 of the MUX / DEMUX 10 of the first embodiment is determined by the incident light 8 immediately before entering the channel waveguide 3 and the branch connection branch 6 of the channel waveguide 3.
1 (integration over the area of overlap bet)
ween the normalized optical field 8 and 81). This calculation method is, for example, "IEEE JOURNA
L OF QUANTUM ELECTRONICS. VOL. 28 No. 12. pp. 2729
(1992) ".

Since the incident light 8 has an electric field intensity distribution of the light diffused by the input slab 2, its width is wide. On the other hand, the electric field intensity distribution 81 is narrow because it is a mode excited by the core 51 having a width of 7 μm. Thus, the coupling loss increases as the ratio of the widths of the electric field strengths to be coupled increases. On the other hand, the MUX / DEMUX 10- of the fourth embodiment is
Since the tip portion of the branch connecting branch 61 used for 3 is thin,
The guided mode 83 excited at the tip portion has a wide width. As a result, the width ratio between the incident light 8 and the electric field intensity distribution 81 becomes small, and the coupling loss decreases.

On the other hand, when the branch connecting / connecting branch 65 having the taper portion 65p is provided as in the fourth embodiment, as shown in FIG. While the electric field strength distribution 8 of the incident light propagating through the slab 2 and reaching the slab boundary line 22 is shown, the electric field strength distribution of the guided mode excited at the tip portion D1 of the branch connection branch 65 is indicated by reference numeral 83. Further, the electric field intensity distribution of the guided mode excited in the portion D2 where the tapered portion 65p of the branch connection branch 65 is finished is as indicated by reference numeral 84.

In FIG. 15 (b), the branch connecting branch 65 is designed such that the taper portion 65p widens the width as the branch connection branch 65 moves away from the tip portion D1. The waveguide width W ₀ in the portion D2 can be set to about 7 μm, the waveguide width W _p in the tip portion D1 can be set to about 2 μm, and the length Lp of the tapered portion 65p can be set to about 2.5 mm.

Here, since the channel waveguide according to the present embodiment is composed of a single mode waveguide,
When the width of the waveguide is smaller than about 1/2, the electric field distribution has a property of widening. That is, as shown in FIGS. 15A and 15B, the electric field intensity distribution 83 of the tip portion D1 of the branch connection branch 65 is wider than the electric field intensity distribution 81 of the corresponding portion of the branch connection branch 61 (that is, The waveform of the intensity distribution becomes flat).

The tip portion D of the branch connection branch 61
The electric field intensity distributions 81 and 84a in the first and the second D2 and the electric field intensity distribution 84 in the tip portion D2 of the branch connection branch 65 have the same core widths of the excited portions, and therefore have the same width and shape. Here, the light coupling efficiency at the slab boundary line 22 of each branch connection branch 61, 65 is determined by the electric field intensity distribution 8 of the incident light and the electric field intensity distribution 81, 83 of each waveguide mode excited in the waveguide. It is equal to the convolution integral [see, for example, Kenji Kawano, "Fundamentals and Applications of Optically Coupled Systems for Optical Devices," Hyundai Kogakusha, page 31, equation (3.1-7)]. The configuration of the connecting branch 65 can obtain a result that the coupling efficiency is higher (that is, the loss is lower) than the configuration of the branch connecting branch 61.

Therefore, by configuring the branch connecting branch 65 having the tapered portion 65p, the input slab 2 and the channel at the slab boundary line 22 can be formed as compared with the case where the branch connecting branch is configured without the tapered portion 65p. The connection loss with the waveguide 3-3 can be reduced. As described above, according to the wavelength demultiplexing device according to the fourth embodiment of the present invention, the channel waveguide 3-3 in the vicinity optically connected to the input slab 2 has two branch connection branches 65. , And the merging portion 69 that optically couples the distributed light from the branch connection branch 65, and has the same advantages as in the case of the first embodiment described above.
However, since the tapered portion 65p is formed so as to have a width that narrows in a taper shape as it approaches the input slab 2, even if the input slab 2 and each of the input slab 2 and the input slab 2 are not provided with the tapered portion 65p. There is an advantage that the connection loss with the channel waveguide 3 can be reduced.

In the fourth embodiment described above, the central axis 33 of the end 6-3 in each channel waveguide 3-3 is used.
Although b is aligned with the optical axis of the incident light, according to the present invention, further, for example, as shown in FIG. The branch connection branch 65 may be configured to be arranged on the extension line.

In other words, the branch connection branch 65 of each channel waveguide 3-3 shown in FIG. 16 is arranged so that its central axis 33a is perpendicular to the tangent of the arc forming the slab boundary line 22. Therefore, by configuring the branch connection branch 65 in this way, the coupling loss can be further reduced and the incident efficiency of the distributed light can be further enhanced, compared with the case of the above-described embodiment.

Further, the MUX / DEMUX1 according to the present invention
0-3 and conventional MUX / DEMUX operation,
A comparison is made with reference to FIGS. 17 and 18. FIG. 17 shows the case of the conventional MAX / DEMUX. In this case, the incident light 8 that is incident from the input waveguide 101 is the channel waveguide 103.
When coupled to the tapered portion 162, the second-order mode light 82 is excited in addition to the zero-order mode light 80a. Here, when the 0th-order mode light 80a propagates through the tapered portion 162 and reaches a narrow portion, it becomes 80b, but the 2nd-order mode light 82 is
As indicated by P22 in the figure, while propagating through the tapered portion 162, the loss is radiated outside the channel waveguide 103.

On the other hand, what is shown in FIG. 18 is in this embodiment. In this case, when the incident light 8 is coupled to the channel waveguide, the 0th-order mode light 80c
Only is excited. The 0th-order mode light 80c light excited by the two branches propagates through the branch connection branch 61 and is combined at the portion where the two branches become one. At this time, the light propagating through the upper branch is represented by the sum of the 0th mode light 80e1 and the 1st mode light 831. The light propagating through the lower branch is represented by the sum of the 0th-order mode light 80e2 and the 1st-order mode light 832. When 831 and 832 are combined with 80e1 and 80e2, 831 and 832 are canceled by each other and disappear. Therefore, there is no loss due to the multiplexing of 831 and 832. Since 80e1 and 80e2 have the same phase in the 0th-order mode, they are mutually strengthened and confined in the channel waveguide 3 to propagate. Therefore,
Unlike the conventional example, the loss due to the radiation of the higher order mode does not occur, and the loss is low.

In the structure shown in FIG. 18, the light propagating through the channel waveguide 3-3 via the input slab 2 is, in the branch connection branch 65, the above-mentioned channel waveguide 10.
The amount of light emitted to the outside of the core is significantly smaller than that of the light propagating in 3-1 and the optical loss can be greatly improved. In this case, the structure shown in FIG. 17 has a loss reduction effect of about -16.4 dB, and the structure shown in FIG. 18 has a loss of about -14.7 dB.

According to the simulation, the wavelength demultiplexing device 10-3 according to the fourth embodiment has a 1.7 dB loss reduction effect more than that of the conventional wavelength demultiplexing device (see FIG. 28). . (E) Description of Fifth Embodiment FIGS. 19 to 21 are views showing a fifth embodiment of the present invention, and FIG. 19 is a MUX / DEMUX 10 functioning as a wavelength demultiplexing device according to the fifth embodiment of the present invention. 4 is a schematic diagram showing a main part of FIG. 4 and is shown by paying attention to a core pattern in an optical waveguide device constituting the wavelength multiplexing / demultiplexing device 10-4, as in the case of each of the above-described embodiments. is there. 20 is an enlarged schematic diagram showing a part of the input waveguide 1, the input slab 2 and the channel waveguide 3-4, and FIG. 21 is one channel waveguide 3-4 on the input slab 2 side. It is a schematic diagram which shows the edge part 6-4.

MUX / DEMUX according to the fifth embodiment
Also in 10-4, as in the case of each of the above-described embodiments,
The core is formed so that the upper, lower, left, and right sides are surrounded by the underclad or the overclad, and light is confined in the core and can propagate. Further, the MUX / DEMUX 10-4 according to the fifth embodiment is different from the above-described fourth embodiment (see reference numeral 10-3) in the configuration of the channel waveguide 3-4, but other than this. The configuration of is the same as that of each of the above-described embodiments. That is, in the core, together with the channel waveguides 3-4 having the characteristics peculiar to the fifth embodiment, the same input waveguide 1, input slab 2, output slab 4, and output waveguide 5 as those in each of the above-described embodiments are provided. The pattern that functions as is integrally formed. 19 to 21.
In the figure, the same reference numerals as those in the drawings showing the above-described respective embodiments indicate almost the same parts.

Further, the channel waveguide 3-4 according to the fifth embodiment is a channel waveguide 3-4 in the vicinity which is optically connected to the input slab 2, that is, the channel waveguide 3-4 on the input slab 2 side. The end 6-4 of 4 has a characteristic core pattern. That is, the MU according to the fifth embodiment
As shown in FIG. 21, the end portion 6-4 of the channel waveguide 3-4 of the X / DEMUX 10-4 (see FIG. 19 or FIG. 20) has a width W _{p at} the connection portion 24 with the input slab 2.
Has a narrow width of 66 s, the width of which is constant until it is separated from the input slab 2 by a constant distance, and a tapered portion 66 p which spreads to W _{0 as the} distance from the input slab 2 increases.

Here, for example, W _{0 is set} to 7 μm, and W _p
Is 2 μm, the connection loss between the input slab 2 and the channel waveguide 3 can be made smaller than the connection loss obtained in the fourth embodiment. Here, the tapered portion 66p is
It has a width that narrows in a taper shape as it approaches the input slab 2 from the confluence portion 69 side, and the constant-width narrow-width waveguide portion 66s optically connects the input slab 2 and the taper portion 66p, and the taper portion 66p. Has the same width as the narrowest part and has a substantially constant width.

Here, the length Lp of the tapered portion 65p is set to 800 m.
The length Ls of the narrow-width waveguide unit 66s having a constant width m can be set to 200 μm. Note that, as shown in FIG. 21, the central axis 33b at the end portion 6-4 of each channel waveguide 3-4 is 2
It passes through the center of the gap portion G1 sandwiched by the branch connecting branches 66 of the book, and its extension passes through the incident light diffusion center 21. In other words, the central axis 33b of the end portion 6-4 in each channel waveguide 3 coincides with the optical axis of the incident light.

In the optical multiplexer / demultiplexer 10-4 according to the fifth embodiment, the branch connection branch 65 as in the fourth embodiment may be provided depending on the case where the taper portion 66p and the constant width narrow waveguide portion 66 are provided. Optical multiplexing / demultiplexing device 10 configured as above
-3, it is possible to further reduce the connection loss between the input slab 2 and the channel waveguide 3-3. here,
The reason why the connection loss between the input slab 2 and the channel waveguide 3 is reduced by the MUX / DEMUX 10-4 according to the fifth embodiment will be described by comparing FIG. 22 (a) and FIG. 22 (b).

FIG. 22A shows the MU in the fifth embodiment.
FIG. 22B is a diagram for explaining the operation of the input side connection unit 6-3 of the X / DEMUX, and FIG. 22B is a diagram for explaining the operation of the input side connection unit 6 of the MUX / DEMUX in the fourth embodiment. Is. Here, the branch 6 shown in FIG.
The electric field distribution excited at the tip D1 of No. 6 is represented by reference numeral 83a.

With respect to the electric field intensity distribution 8 of the light radiated from the input waveguide 1 and propagating through the input slab 2 and reaching the slab boundary line 22 shown in FIG.
The electric field intensity distribution of the guided mode excited at the tip portion D1 of the above is indicated by reference numeral 83, and the electric field intensity distribution of the guided mode excited at the portion D2 where the tapered portion 65p of the branch connection branch 65 ends. Is as indicated by reference numeral 84.

Here, as shown in FIG. 22B, the first
In the case of the branch connection branch 65 used in the MUX / DEMUX 10 of the embodiment, the width of the branch connection branch 65 is minimum (2 μm).
Only the part of the slab boundary line 22 becomes. In order for the light propagating through the branch connection branch 65 to have an electric field intensity distribution corresponding to a core width of 2 μm, it is necessary that the light propagates through the core at least a distance longer than the wavelength. Here, in practice, it is necessary for the light to propagate through the core having a length of 10 times the wavelength or more.

However, the branch connecting branch 6 shown in FIG.
The length of the portion of 5 having a width of 2 μm is as close as possible to 0, which is shorter than the required length. It becomes narrower than the width of the excited electric field strength distribution. As a result, the coupling loss becomes larger than the coupling loss expected when the width of the branch connection branch 65 is 2 μm.

On the other hand, in the case of FIG. 22A corresponding to the input side connecting portion 6-4 of the fifth embodiment, the core width of the tip end of the branch connecting branch 66 is set to 10 times the wavelength or more. It can be constant at 2 μm over the length. Therefore, the electric field distribution excited at the tip D1 of the branch 66 extends to the electric field distribution 83a having a width corresponding to the case where the waveguide width is 2 μm. The electric field distribution changes while the light propagates through the tapered portion 66p, and when the light reaches the portion D2 where the tapered portion 66p ends, the electric field intensity becomes 84. As a result, the coupling loss between the input slab 2 and the channel waveguide 3 is reduced to a value corresponding to the case where the width of the branch connection branch 66 is 2 μm.

The length Lp of the taper portion 65p is 800 mm.
The length Ls of the constant width narrow-width waveguide portion 66s can be set to about 200 μm. In the fifth embodiment described above, the central axis 33b of the end portion 6-4 in each channel waveguide 3-4 coincides with the optical axis of the incident light. However, according to the present invention, For example, like the channel waveguide 3-4a shown in FIG. 23, the branch connection branch 66a may be configured such that the central axis 33a is arranged on an extension line from the incident light diffusion center 21.

In other words, the branch connecting branch 66a of each channel waveguide 3-4a shown in FIG.
It can be arranged so that a is perpendicular to the tangent of the arc forming the slab boundary line 22. By thus configuring the branch connection branch 66a, it is possible to further reduce the coupling loss and further increase the incident efficiency of the distributed light, as compared with the case of the above-described embodiment.

(F) Others The MUX / DEMUX according to the third embodiment described above.
In the MUX / DEMUX 10-2 that functions as a waveguide, the primary branch connecting branch 611 of the end 6-2 in each channel waveguide 3-2 is a waveguide with a constant width such that its central axes 32b are parallel. However, according to the present invention, the invention is not limited to this.
Each channel waveguide 3-21 in the mode as shown in FIG.
End portions 6-21 to 6-24 of 3-24 can be configured.

That is, as shown in FIG. 24, with respect to the end portion 6-21 of each channel waveguide 3-21, the primary branch connecting branch 6 having the same tapered portion 65p as in FIGS.
51 may be provided, and such a configuration has the same advantages as the case of the above-described fourth embodiment. Furthermore, for example, as shown in FIG. 25, in the case of the fourth embodiment, the primary branch connection branch 651 at the end 6-22 of each channel waveguide 3-22 is used (see FIGS. 12 to 14).
The taper portion 65p may be provided in the same manner as the above, and the central axis 32c thereof may be configured to coincide with the optical axis of the incident light. With this configuration, the same advantages as in the case of the fourth embodiment can be obtained. Besides, as in the case of FIG. 11, it contributes to further reducing the coupling loss between the input slab 2 and the channel waveguide 3-2.

Further, for example, as shown in FIG. 26, the primary branch connection branch 661 at the end 6-23 of each channel waveguide 3-23 is the same as in the case of the fifth embodiment (see FIGS. 19 to 21). A primary branch connection branch 661 including a similar tapered portion 66p and a constant width portion 66s may be configured, and by configuring in this way, the same advantages as in the case of the fifth embodiment described above can be obtained. You can also get

Furthermore, as shown in FIG. 27, for example, the primary branch connection branch 661 at the end 6-24 of each channel waveguide 3-24 is used in the case of the fifth embodiment (FIGS. 19-21).
(See FIG. 3), each of the branch connecting branches 661 has a central axis 3 and a tapered portion 66p and a constant width portion 66s.
2c may be configured to coincide with the optical axis of the incident light,
With this configuration, in addition to the same advantages as in the case of the fifth embodiment, the coupling loss between the input slab 2 and the channel waveguide 3-2 is further reduced as in the case of FIG. 11. Contribute.

Furthermore, it is of course possible to apply the low-refractive-index island region 34 in the above-described second embodiment to the channel waveguide of another embodiment other than the second embodiment. Furthermore, according to the present invention, in addition to the embodiments disclosed in the above-described embodiments, various modifications can be carried out without departing from the spirit of the present invention.

(G) Additional Notes (Additional Note 1) A first waveguide for propagating wavelength-multiplexed light of a plurality of channels, and a first slab for diffusing light input from the first waveguide, on a substrate, A plurality of channel waveguides whose lengths are sequentially set with a predetermined waveguide length difference, distribute and input the light diffused in the first slab, and propagate, and each distribution propagated in the channel waveguides. Enter the light,
A second slab that collects the wavelength-separated light and a second waveguide that propagates the light collected by the second slab are formed, and the channel waveguide and the first slab are formed. The wavelength demultiplexing device is characterized in that the number of connection points for optically connecting the two is larger than the number of connection points for connecting the channel waveguide and the second slab.

(Supplementary Note 2) A first waveguide that propagates wavelength-multiplexed light of a plurality of channels, a first slab that diffuses the light input from the first waveguide, and a predetermined waveguide on a substrate. The lengths are sequentially set with a difference in length, a plurality of channel waveguides that distribute and input the light diffused in the first slab and propagate, and the respective distributed lights propagated in the channel waveguides are input. A second slab that collects the wavelength-separated light and a second waveguide that propagates the light collected by the second slab are formed, and the second slab is optically formed on the first slab. The channel waveguide in the vicinity to be connected has a plurality of branch connection branches for inputting the distributed light from the first slab, and a confluence section for optically coupling the distributed light from the branch connection branches. Characterized by being integrally formed,
Wavelength demultiplexer.

(Supplementary Note 3) The branch connection branch is configured to have a width such that the higher-order mode light of the distributed light that is input is cut off, and the coupling contact at the merging portion is input. The wavelength demultiplexing device according to appendix 2, wherein the wavelength demultiplexing device is formed so as to have a width capable of exciting the higher-order mode light of the distributed light. (Supplementary Note 4) The branch connecting branch is first from the merging portion side.
The wavelength demultiplexing device according to appendix 2 or 3, wherein the wavelength demultiplexing device is formed so as to have a width that narrows in a taper shape as it approaches the slab.

(Supplementary Note 5) The branch connecting branch optically has a taper portion having a width narrowing in a taper shape as it approaches the first slab from the confluence portion side, and the first slab and the taper portion optically. Supplementary Note 2, characterized in that it is constituted by a constant-width narrow-width waveguide that is connected and has a width that is approximately the same as the narrowest width of the tapered portion and has a substantially constant width.
Or the wavelength demultiplexing device described in 3.

(Supplementary Note 6) A first waveguide for propagating wavelength-multiplexed light of a plurality of channels, a first slab for diffusing light input from the first waveguide, and a predetermined waveguide on a substrate. The lengths are sequentially set with a difference in length, a plurality of channel waveguides that distribute and input the light diffused in the first slab and propagate, and the respective distributed lights propagated in the channel waveguides are input. A second slab that collects the wavelength-separated light and a second waveguide that propagates the light collected by the second slab are formed, and the second slab is optically formed on the first slab. The channel waveguide in the vicinity to be connected optically couples a plurality of primary branch connection branches for inputting the distributed light from the first slab and the distributed light from the primary branch connection branches. A plurality of sets of primary coupling portions having primary merging portions, and the primary coupling portions. A secondary coupling unit having a plurality of secondary branch connection branches for inputting the coupled distributed light and a secondary merging unit for optically coupling the distributed light from the secondary branch connection branches. A wavelength demultiplexing device, characterized by being integrally formed with.

(Supplementary Note 7) The primary branch connection branch is configured to have a width such that the higher-order mode light of the input distributed light is cut off, and the coupling contact in the merging portion is 7. The wavelength demultiplexing device according to appendix 6, wherein the wavelength demultiplexing device is formed so as to have a width capable of exciting the higher-order mode light of the input distributed light. (Supplementary Note 8) The branch connecting branch is the first from the merging portion side.
8. The wavelength demultiplexing device according to appendix 6 or 7, wherein the wavelength demultiplexing device is formed so as to have a width that narrows in a taper shape as it approaches the slab.

(Supplementary Note 9) The branch connecting branch optically has a taper portion having a width narrowing in a taper shape as it approaches the first slab from the side of the merging portion and the first slab and the taper portion. Supplementary Note 6 characterized in that it is constituted by a constant-width narrow-width waveguide that is connected and has a width that is approximately the same as the width of the narrowest width of the above-mentioned tapered portion and has a substantially constant width.
Or the wavelength demultiplexing device described in 7.

(Supplementary Note 10) A first waveguide for propagating wavelength-multiplexed light of a plurality of channels, a first slab for diffusing light input from the first waveguide, and a predetermined waveguide on a substrate. The lengths are sequentially set with a difference in length, a plurality of channel waveguides that distribute and input the light diffused in the first slab and propagate, and the respective distributed lights propagated in the channel waveguides are input. A second slab that collects the wavelength-separated light and a second waveguide that propagates the light collected by the second slab are formed, and the channel waveguide The connection point with one slab is formed to have a width in which the higher-order mode light of the distributed light can be excited, and to have a width that narrows in a taper shape with increasing distance from the first slab. Also, the island-shaped formation region having a low refractive index is A wavelength demultiplexing device, characterized in that it is provided so as to partition a plurality of channel waveguides in the vicinity optically connected to the lab.

(Additional remark 11) The channel waveguide partitioned by the island-shaped formation region is configured as a waveguide in which the higher-order mode light of the distributed light that is input is cut off, and the partitioned channel The waveguide width of the portion where the waveguides are coupled is formed so as to have a width in which the higher-order mode light of the input distributed light can be excited.
The wavelength demultiplexing device according to attachment 10.

(Supplementary Note 12) The supplementary note 1 is characterized in that the connection interface with the channel waveguide in the first slab is formed in an arc shape centered on the diffusion center of the light diffusely input. 11. The wavelength demultiplexing device according to any one of 1 to 11. (Supplementary note 13) The supplementary note 12, characterized in that the central axis of the channel waveguide in the vicinity optically connected to the first slab is arranged on an extension line from the diffusion center. Wavelength demultiplexer.

(Supplementary Note 14) The connection interface with the channel waveguide in the first slab is formed in an arc shape centered on the diffusion center of the light diffusely input.
6. The wavelength demultiplexing device according to any one of appendices 2 to 5, wherein the central axis of each branch connection branch is arranged on an extension line from the diffusion center. (Supplementary Note 15) The connection interface with the channel waveguide in the first slab is formed in an arc shape centered on the diffusion center of the light that is diffused and input, and the central axis of each primary branch connection branch is The wavelength demultiplexing device according to Appendix 7, wherein the wavelength demultiplexing device is arranged on an extension line from the diffusion center.

(Supplementary Note 16) A first waveguide that propagates wavelength-multiplexed light of a plurality of channels, a first slab that diffuses the light input from the first waveguide, and a predetermined waveguide on a substrate. The lengths are sequentially set with a difference in length, a plurality of channel waveguides that distribute and input the light diffused in the first slab and propagate, and the respective distributed lights propagated in the channel waveguides are input. A second slab that collects the wavelength-separated light and a second waveguide that propagates the light collected by the second slab are formed, and the second slab is optically formed on the first slab. The channel waveguide in the vicinity to be connected is formed so that the coupling waveguides for optically coupling and propagating a plurality of distributed lights are tandemly connected in a multi-stage tree shape. Branching device.

(Supplementary Note 17) An input waveguide for guiding and outputting wavelength-multiplexed light composed of light of a plurality of wavelengths, a first slab for diffusing the wavelength-multiplexed light output from the input waveguide, and the first The waveguide is composed of a plurality of waveguides for separating wavelength-multiplexed light diffused in a slab according to the plurality of wavelengths and propagating the separated light, and the plurality of waveguides are adjacent waveguides of the plurality of waveguides. A plurality of channel waveguides formed so that the difference in optical path length between them is constant, and an output slab that converges a plurality of separated lights from the plurality of channel waveguides. , Wavelength demultiplexer.

(Supplementary Note 18) A first portion, which is located in the vicinity of the first slab, of the portions forming the plurality of channel waveguides
18. The wavelength demultiplexing device according to appendix 17, wherein the shape of the slab boundary line is a circular arc having a predetermined radius centered on the diffusion center portion provided in the first slab. (Supplementary note 19) The wavelength demultiplexing device according to supplementary note 18, wherein the first slab is configured to diffuse and output the wavelength-multiplexed light in the same phase from the diffusion center portion.

(Supplementary Note 20) The supplementary note 17 is characterized in that each of the plurality of channel waveguides is configured such that each of the separated lights causes a phase difference based on a difference in the optical path length. Wavelength demultiplexer. (Supplementary Note 21) Each of the plurality of channel waveguides is
18. The wavelength demultiplexing device according to appendix 17, characterized in that the difference in optical path length is set to an order that is an integral multiple of the center wavelength included in the wavelength multiplexed light.

(Additional remark 22) Of the parts constituting the plurality of channel waveguides, the second one located near the second slab
18. The wavelength demultiplexing device according to appendix 17, wherein the shape of the slab boundary line is a circular arc having a predetermined radius. (Supplementary Note 23) The second slab converges the plurality of separated lights based on a wavelength of light output from the second slab boundary line and a central wavelength included in the wavelength-multiplexed light. 23. The wavelength demultiplexing device according to appendix 22, which is configured.

(Appendix 24) At least two terminals are provided,
One of the terminals is provided at a converging position of light having a desired wavelength, and the other terminal is provided with a second waveguide used as an output terminal. The wavelength demultiplexing device according to any one of claims.

[0134]

As described in detail above, the wavelength demultiplexing device of the present invention has the following operational effects and advantages. 1. The distances dc11 and dc12 at the connection points where the channel waveguide and the first slab are optically connected, in other words, the angular pitch of the distributed light incident on the end channel waveguide of the channel waveguide on the first slab side. Since the width is made narrow, the connection loss between the first slab and the channel waveguide can be reduced.

2. Even when the sizes of the first slab and the second slab are made symmetrical, the channel waveguide and the first slab are kept wide while keeping a wide space dc2 between the connection points where the channel waveguide and the second slab are optically connected. Since the distance (dc11 and dc12) between the connection points where and are optically connected can be narrowed, interference (coupling) of light propagating in the channel waveguide can be prevented in the vicinity of the second slab, and device design can be facilitated. However, there is an advantage that the connection loss between the first slab and the channel waveguide can be reduced.

3. The width of the branch connection branch is formed to have a width W2 that cuts off the higher-order mode light of the distributed light input from the first slab, and the width W1 of the coupling contact at the merging portion is input. Since the high-order mode light is formed to have a width capable of being excited, there is also an advantage that the loss due to the excitation of the higher-order mode can be suppressed.

4. The channel waveguide partitioned by the island-shaped formation region is formed so that the higher-order mode light of the distributed light input from the first slab is cut off,
Since the width of the confluence is formed so as to be the width in which the higher-order mode light of the input distributed light is excited, there is also an advantage that the loss due to the excitation of the higher-order mode can be suppressed. 5. Since the first slab-side end of each channel waveguide is tandem-connected to the primary coupling part and the secondary coupling part on a tree of a plurality of stages, one channel waveguide 3-2 is the first.
The slab 2 can be integrally formed with two or more (in this case, four) connection points, which has the advantage of reducing the coupling loss between the first slab and the channel waveguide, and the second slab and the channel. It is possible to increase the channel waveguide interval at the connection portion with the waveguide, further suppress optical interference at the end of the channel waveguide, and particularly a waveguide with a small refractive index difference where optical interference (coupling) easily occurs. Is effective in preventing interference (coupling) when using.

6. The channel waveguide in the vicinity optically connected to the first slab is formed by integrally forming two branch connection branches and a merging portion that optically couples the distributed light from the branch connection branches, Further, since the branch connecting branch is formed by the tapered portion so as to have a width that narrows in a taper shape as it approaches the first slab, the first slab can be compared with the case where the tapered portion is not provided. There is an advantage that the connection loss between the channel waveguide and each channel waveguide can be reduced.

7. The channel waveguide in the vicinity portion optically connected to the first slab is formed by integrally forming two branch connection branches and a merging portion that optically couples the distributed light from the branch connection branches, Further, since the branch connection branch includes the tapered portion and the constant width narrow-width waveguide portion, the first slab and each There is an advantage that the connection loss with the channel waveguide can be further reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a wavelength multiplexing / demultiplexing device that functions as a wavelength demultiplexing device according to a first embodiment.

FIG. 2 is a schematic diagram showing a main part of the wavelength division multiplexer according to the first embodiment.

FIG. 3 is a schematic diagram showing a main part of a wavelength division multiplexer according to the first embodiment.

FIG. 4A is a diagram for explaining the propagation of light in a channel waveguide of a conventional wavelength multiplexing / demultiplexing device, and FIG.
[Fig. 3] is a schematic diagram for explaining an operation effect of the wavelength division multiplexer in the first embodiment.

FIG. 5 is a schematic diagram showing a main part of a wavelength multiplexing / demultiplexing device according to a modification of the first embodiment.

FIG. 6 is a schematic diagram showing a wavelength multiplexing / demultiplexing device that functions as a wavelength demultiplexing device according to a second embodiment.

FIG. 7 is a schematic diagram showing a main part of a wavelength division multiplexer according to a second embodiment.

FIG. 8A is a diagram for explaining the propagation of light in the channel waveguide of the conventional wavelength division multiplexer, and FIG.
[Fig. 6] is a schematic diagram for explaining the function and effect of the wavelength division multiplexer according to the second embodiment.

FIG. 9 is a schematic diagram showing a wavelength multiplexing / demultiplexing device that functions as a wavelength demultiplexing device according to a third embodiment.

FIG. 10 is a schematic diagram showing a main part of a wavelength division multiplexer according to a third embodiment.

FIG. 11 is a schematic diagram showing a main part of a wavelength multiplexing / demultiplexing device according to a modification of the third embodiment.

FIG. 12 is a schematic diagram showing a wavelength multiplexing / demultiplexing device that functions as a wavelength demultiplexing device according to a fourth exemplary embodiment.

FIG. 13 is a schematic diagram showing a main part of a wavelength division multiplexer according to a fourth embodiment.

FIG. 14 is a schematic diagram showing a main part of a wavelength division multiplexer according to a fourth embodiment.

FIG. 15A is a diagram for explaining the operation of the input-side connection section of the wavelength division multiplexer according to the fourth embodiment,
(B) is a figure for demonstrating operation | movement of the input side connection part of the wavelength division multiplexer in 1st Embodiment.

FIG. 16 is a schematic diagram showing a main part of a wavelength division multiplexer according to a modification of the fourth embodiment.

FIG. 17 is a diagram for explaining the propagation of light in the channel waveguide of the conventional wavelength division multiplexer.

FIG. 18 is a diagram for explaining the function and effect of the wavelength division multiplexer in the modification of the fourth embodiment.

FIG. 19 is a schematic diagram showing a wavelength multiplexing / demultiplexing device that functions as a wavelength demultiplexing device according to a fifth exemplary embodiment.

FIG. 20 is a schematic diagram showing a main part of a wavelength division multiplexer according to a fifth embodiment.

FIG. 21 is a schematic diagram showing a main part of a wavelength division multiplexer according to a fifth embodiment.

22A is a schematic diagram for explaining the function and effect of the wavelength division multiplexer according to the fifth embodiment, and FIG. 22B is a channel guide of the wavelength division multiplexer shown in FIGS. 12 and 13. It is a figure for demonstrating the propagation of the light in a waveguide.

FIG. 23 is a schematic diagram showing a main part of a wavelength division multiplexer according to a modification of the fifth embodiment.

FIG. 24 is a schematic diagram showing another embodiment of a wavelength multiplexing / demultiplexing device that functions as a wavelength demultiplexing device of the present invention.

FIG. 25 is a schematic view showing another embodiment of the wavelength division multiplexing / demultiplexing device that functions as the wavelength division multiplexing device of the present invention.

FIG. 26 is a schematic view showing another embodiment of the wavelength division multiplexer, which functions as the wavelength division multiplexer of the present invention.

FIG. 27 is a schematic diagram showing another embodiment of the wavelength division multiplexing / demultiplexing device functioning as the wavelength division multiplexing device of the present invention.

FIG. 28 is a block diagram showing a configuration of a conventional AWG type wavelength division multiplexer.

29A is a schematic diagram showing the shape of a waveguide of an AWG type wavelength multiplexer / demultiplexer, FIG. 29B is a diagram showing a configuration example of a conventional spectroscopic device, and FIG. It is a figure which shows the correspondence of the wavelength multiplexing / demultiplexing apparatus comprised using the waveguide and the component of the conventional spectroscopy apparatus.

FIG. 30 (a) and FIG. 30 (b) are diagrams showing three adjacent channel waveguides among a plurality of channel waveguides.

FIG. 31 is a diagram showing an example of a spectroscopic device and insertion loss of a wavelength multiplexing / demultiplexing device.

32 (a) to 32 (c) are diagrams for explaining the factors causing the insertion loss in the connection portion between the first slab and the channel waveguide.

FIG. 33 (a) is a diagram showing a first technique for reducing insertion loss, and FIG. 33 (b) is a diagram explaining its action.

FIG. 34A is a diagram showing a second technique for reducing the insertion loss, and FIG. 34B is a diagram explaining the action thereof.

FIG. 35 is a diagram showing how higher-order mode light is excited in the channel waveguide and radiated to the outside of the core.

[Explanation of symbols]

1 Input Waveguide (First Waveguide) 2 Input Slab (First Slab) 3, 3-1 to 3-4, 3-4a, 3-21 to 3-24
Channel waveguide 4 Output slab (second slab) 5 Output waveguide 6, 6-1 to 6-4, 6-21 to 6-24 End portion 7 End portion 8 Electric field intensity distribution 10, 10-1 of incident light 10-4 Wavelength multiplexer / demultiplexer 21 Incident light diffusion centers 22, 42 Slab boundary lines 24, 44 Connection parts 31, 33b End central axes 32a, 32c, 33a Branch connection central axis 34 Low refractive index island formation Region 61 Branch connection branch 61a-1, 61a-2 Waveguide 62a Tapered connection branch 65, 66, 66a Branch connection branch 65p, 66p Tapered portion 66s Width constant narrow width waveguide portion 69 Merging portion 80a, 80b Zero-order mode 82 Secondary mode 83, 84, 84a Electric field intensity distribution 85 Light propagated through waveguide 86 Light scattered and lost 100 Substrate 100A Surrounding region 101 Input waveguide 102, 102-1 Input slab 103, 10 -1 channel waveguide 104 output slab 105 output waveguides 106, 106-1 wavelength multiplexing / demultiplexing device 107 input side connection unit 110 spectroscopic device 113 diffraction gratings 131 to 133 channel waveguides 122,142 slab boundary line 162 tapered connection branch 610 primary coupling part 611 primary branch connection branch 612 primary merging part 620 secondary coupling part 621 secondary branch connection branch 622 secondary merging part

Continued front page    F term (reference) 2H047 KA03 KA12 KA13 LA01 LA19                       TA33 TA34

Claims (10)

[Claims] 1. A first waveguide that propagates wavelength-multiplexed light of a plurality of channels on a substrate, a first slab that diffuses the light input from the first waveguide, and a predetermined waveguide length difference. The length is set sequentially with the
A plurality of channel waveguides for distributing and propagating the light diffused in the slab, and a second slab for collecting the wavelength-separated light by inputting the respective distributed lights propagated in the channel waveguide A second waveguide for propagating the light condensed by the second slab is formed, and the number of connection points optically connecting the channel waveguide and the first slab is The wavelength demultiplexing device is configured so as to be larger in number than the number of connection points where the channel waveguide and the second slab are connected. 2. A first waveguide for propagating wavelength-multiplexed light of a plurality of channels, a first slab for diffusing light input from the first waveguide, and a predetermined waveguide length difference on a substrate. The length is set sequentially with the
A plurality of channel waveguides for distributing and propagating the light diffused in the slab, and a second slab for collecting the wavelength-separated light by inputting the respective distributed lights propagated in the channel waveguide , A second waveguide for propagating the light condensed by the second slab, and a channel waveguide in a vicinity portion optically connected to the first slab is the first slab. A plurality of branch connection branches for inputting the distributed light from the branch connection, and a merging portion that optically couples the distributed light from the branch connection branches. Wave device. 3. The branch connection branch is configured to have a width such that the higher-order mode light of the input distributed light is cut off, and the coupling contact at the merging portion is input to the distributed connection. The wavelength demultiplexing device according to claim 2, wherein the wavelength demultiplexing device is formed to have a width capable of exciting the higher-order mode light. 4. The wavelength according to claim 2, wherein the branch connection branch is formed to have a width that narrows in a taper shape as it approaches the first slab from the confluence portion side. Branching device. 5. The tapered connecting branch optically connects the tapered portion having a width that narrows in a taper shape as it approaches the first slab from the side of the merging portion and the first slab and the tapered portion. A constant-width narrow-width waveguide having a width substantially equal to that of the narrowest width of the tapered portion and a substantially constant width,
It is comprised by this, The claim 2 or 3 characterized by the above-mentioned.
The wavelength demultiplexing device described. 6. A first waveguide that propagates wavelength-multiplexed light of a plurality of channels on a substrate, a first slab that diffuses light input from the first waveguide, and a predetermined waveguide length difference. The length is set sequentially with the
A plurality of channel waveguides for distributing and propagating the light diffused in the slab, and a second slab for collecting the wavelength-separated light by inputting the respective distributed lights propagated in the channel waveguide , A second waveguide for propagating the light condensed by the second slab, and a channel waveguide in the vicinity optically connected to the first slab are the first slab. Of a plurality of primary branch connection branches for inputting the distributed light from the primary branch connection branch and a plurality of primary merging portions for optically coupling the distributed light from the primary branch connection branch A coupling section, a plurality of secondary branch connection branches for inputting the distributed light coupled by the primary coupling section, and a secondary merging for optically coupling the distributed light from the secondary branch connection branches. And a secondary coupling portion having a portion, are integrally formed. That, wavelength demultiplexing device. 7. The primary branch connection branch is configured to have a width such that the higher-order mode light of the distributed light that is input is cut off, and the coupling contact at the merging portion comprises:
7. The wavelength demultiplexing device according to claim 6, wherein the wavelength demultiplexing device is formed so as to have a width capable of exciting the higher-order mode light of the input distributed light. 8. The wavelength according to claim 6, wherein the branch connecting branch is formed to have a width that narrows in a taper shape from the merging portion side toward the first slab. Branching device. 9. The branch connecting branch optically connects the taper portion having a width narrowing in a taper shape as it approaches the first slab from the merging portion side and the first slab and the taper portion. A constant-width narrow-width waveguide having a width substantially equal to that of the narrowest width of the tapered portion and a substantially constant width,
It is comprised by this, The Claim 6 or 7 characterized by the above-mentioned.
The wavelength demultiplexing device described. 10. A first waveguide that propagates wavelength-multiplexed light of a plurality of channels on a substrate, a first slab that diffuses light input from the first waveguide, and a predetermined waveguide length difference. The length is set sequentially with the
A plurality of channel waveguides for distributing and propagating the light diffused in the slab, and a second slab for collecting the wavelength-separated light by inputting the respective distributed lights propagated in the channel waveguide , A second waveguide for propagating the light condensed by the second slab is formed, and the channel waveguide is connected to the first slab by a higher-order mode light of distributed light. The first slab has an island-shaped formation region having a width that can be excited and a width that narrows in a taper shape with increasing distance from the first slab and has a lower refractive index than the channel waveguide. Is provided so as to partition into a plurality of channel waveguides in the vicinity optically connected to
Wavelength demultiplexer.