JP3246710B2 - Optical device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical device using an arrayed waveguide type optical wavelength multiplexer / demultiplexer.

[0002]

2. Description of the Related Art In the field of optical communication, a method (wavelength division multiplexing) of enlarging information capacity by mounting a plurality of signals on light having different wavelengths and transmitting the signals through one optical fiber is being studied.

In this method, a multiplexer / demultiplexer that multiplexes or demultiplexes light of different wavelengths by a diffraction grating plays an important role. In particular, an optical wavelength multiplexer / demultiplexer using an arrayed waveguide diffraction grating is promising because it can increase the number of multiplexed communication capacities at narrow wavelength intervals.

In recent years, attempts have been made to increase the number of multiplexes in a wavelength division multiplexing transmission system to dramatically increase the transmission capacity. To realize this, the wavelength interval is 1
A multiplexer / demultiplexer capable of multiplexing / demultiplexing a plurality of signal lights of about nanometer or less is required.

However, in the conventional optical wavelength multiplexer / demultiplexer using a diffraction grating, the available diffraction orders are limited.
Since sufficient dispersion could not be obtained, the wavelength interval could not be reduced to 1 nanometer or less.

[0006] As an effective method for solving the above problems,
A method using an arrayed waveguide diffraction grating is known.
(JP-A-4-116607, JP-A-4-163406)
JP-A-4-326308 and JP-A-5-1579
FIG. 5 is a plan view of a conventional one-input, N-output optical wavelength multiplexer / demultiplexer using an arrayed waveguide diffraction grating, and FIG.
(A) is a cross-sectional view taken along the line AA of FIG. 5, and (b) of FIG.
6B is a sectional view taken along line CC of FIG. 5, and FIG.
(D) is a sectional view taken along line DD of FIG. 5.

The configuration of a conventional optical wavelength multiplexer / demultiplexer will be described below with reference to FIGS.

This optical wavelength multiplexer / demultiplexer is formed on a substrate 201, and includes an input waveguide 202, an input side slab waveguide 203, an arrayed waveguide diffraction grating 204, and an output side slab waveguide. 205 and N output waveguides 206. In this optical wavelength multiplexer / demultiplexer, a buffer layer 207 is formed on a substrate 201, and a waveguide (core) 208 is formed on the buffer layer 207 using a material having a slightly higher refractive index than the buffer layer 207. Is embedded in a cladding 209 having a refractive index slightly lower than that of the core 208. Also, the arrayed waveguide diffraction grating 20
Reference numeral 4 denotes a plurality of channel waveguides 2 each having a different length ΔL.
10. The input slab waveguide 203 and the output slab waveguide 205 have a flat plate structure having a confinement effect only in the film thickness direction.

FIG. 7 is a diagram showing the principle of wavelength demultiplexing of an arrayed waveguide diffraction grating type wavelength multiplexer / demultiplexer.

Hereinafter, the principle of wavelength demultiplexing will be described with reference to FIG. Consider a case where wavelength-division multiplexed light λ211 in which N waves of wavelengths λ1 and λ2 are wavelength-multiplexed is demultiplexed into N output waveguides 206, respectively. The wavelength multiplexed light 211 incident on the input waveguide 202 propagates through the input waveguide 202 and is diffracted by the input side slab waveguide 203. At this time, since the array waveguide side end face 212 has the center of curvature 216 at the connection point between the input waveguide 202 and the input side slab waveguide 203, the diffracted wavelength-division multiplexed light 211 is in phase with the array waveguide diffraction grating. 204.

The wavelength multiplexed light 211 incident on each channel waveguide 210 of the arrayed waveguide diffraction grating 204
Propagates through each channel waveguide 210 and enters the output side slab waveguide 205. However, a plurality of channel waveguides 21 constituting the arrayed waveguide diffraction grating 204
Since 0 has different lengths, the phase at each channel waveguide 210 differs at the array waveguide side end surface 214 of the output side slab waveguide. Assuming that the waveguide length difference of the arrayed waveguide diffraction grating 204 is ΔL, the phase φ between adjacent channel waveguides is φ = 2πneΔL / λ (1) where ne is the effective refractive index of the channel waveguide. This equation indicates that the phase between the channel waveguides depends on the wavelength of the wavelength multiplexed light 211. Differentiating the equation (1) with respect to the wavelength λ results in δφ = −2πneΔLδλ / λ2 (2), which indicates that there is a proportional relationship between the wavelength dependence δφ of the phase and the wavelength change δλ.

Accordingly, the equal phase plane 213 of the wavelength multiplexed light 211 propagating through the arrayed waveguide diffraction grating 204 is inclined with respect to the arrayed waveguide side end face 214 of the output side slab waveguide 205. Assuming that the interval between the channel waveguides constituting the arrayed waveguide diffraction grating 204 at the arrayed waveguide side end surface 214 is s, the slope δ of the phase plane with respect to the wavelength δλ
θ is given by δθ = −tan ⁻¹ {ΔLδλ / (sλ)} (3) from the equation (2). Since the phase surface is concave, the wavelength-division multiplexed light 211 is focused on the output waveguide side end surface 215 of the output side slab waveguide 205. Therefore, the output waveguide 20
6 are arranged at an angular interval δθ about the center of curvature 217 to separate the wavelength-division multiplexed light 211.

[0013]

However, the optical wavelength multiplexer / demultiplexer is very sensitive to process deviation, and has a problem that the center wavelength of each output waveguide deviates from a design value. Further, there is a problem that the center wavelength varies among the waveguide elements.

Accordingly, an object of the present invention is to provide a method of manufacturing an optical device using an optical wavelength multiplexer / demultiplexer capable of correcting a center wavelength shift and a variation of the center wavelength in the optical wavelength multiplexer / demultiplexer.

[0015]

According to the present invention, an input waveguide and an output waveguide for correcting a center wavelength are formed on both sides of an input waveguide and an output waveguide of an arrayed waveguide type optical wavelength multiplexer / demultiplexer.
It is a solution to use an input waveguide for correction or an output waveguide for correction, wherein a substrate, a plurality of input waveguides formed on the substrate, and a connection to the input waveguide are provided. An input slab waveguide having a flat plate structure, and a waveguide connected to the input waveguide and having a waveguide length of Li (i = 1, 2, 3,.
..) an arrayed waveguide grating composed of a plurality of channel waveguides, an output slab waveguide connected to the arrayed waveguide grating, and a plurality of outputs connected to the output slab waveguide. Prepare an optical wavelength multiplexer / demultiplexer with a waveguide
And one input for connecting to the input waveguide.
Side optical fiber and output for connection to said output waveguide
Preparing fewer output optical fibers than the number of waveguides
The center wavelength of the wavelength split into the output optical fiber is
Any one of the plurality of input waveguides is used so as to have a desired value.
The input side optical fiber is connected to the plurality of output waveguides.
The feature is that each output optical fiber is connected to the gap
This is a method for manufacturing an optical device.

[0016]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the configuration of an arrayed waveguide diffraction grating type optical wavelength multiplexer / demultiplexer having a center wavelength correcting function as one embodiment of the present invention.

The configuration of the optical wavelength multiplexer / demultiplexer according to the present invention will be described below with reference to FIG. This optical wavelength multiplexer / demultiplexer is mounted on the substrate 10
1, an input waveguide 102, a correction input waveguide 103 as a preliminary input, an input side slab waveguide 104, an arrayed waveguide diffraction grating 105, and an output side slab waveguide 10.
6, an output waveguide 107, and a correction output waveguide 108 as a preliminary output.

The input waveguide 102 is a channel waveguide having a rectangular cross-sectional structure, and is arranged along the input waveguide side end face 109 of the input slab waveguide 104. The correction input waveguide 103 is a channel waveguide having a rectangular cross-sectional structure, and is arranged on both sides of the input waveguide 102.

The input side slab waveguide 104 has a flat plate structure without any lateral confinement structure. Input waveguide side end face 10
9 and the end face 110 on the side of the arrayed waveguide grating have arc shapes having centers of curvature 111 and 112 on opposing end faces, respectively. Further, the input waveguide 102 and the correction input waveguide 103 are connected to the center of curvature 11 of the input side slab waveguide 104.
1 are arranged radially.

The arrayed waveguide diffraction grating 105 is composed of a plurality of channel waveguides 122 having a rectangular cross section.
Each channel waveguide 122 has a length ΔL (constant value)
And are arranged in order of length. The dimensions of these channel waveguides 122 are designed to satisfy the single mode condition in the used wavelength band. In the vicinity of the input side slab waveguide 104, the core width has a tapered structure that gradually increases toward the input side slab waveguide 104, and is arranged radially from the center of curvature 112 of the input side slab waveguide 104. ing. Also, in the vicinity of the output side slab waveguide 106, similarly, the core width has a tapered structure in which the core width gradually increases toward the output side slab waveguide 106, and radially extends from the center of curvature 114 of the output side slab waveguide 106. Are located.

The output-side slab waveguide 106 has a flat plate structure similar to the input-side slab waveguide 104 and has no lateral confinement structure. The output waveguide-side end face 115 and the array waveguide-side end face 113 have an arc shape having centers of curvature 116 and 114 on opposing end faces, respectively.

The output waveguide 107 has a rectangular cross section N
The output slab waveguide 106 is formed along the output waveguide end face 115 of the output slab waveguide 106. The correction output waveguide 108 is a channel waveguide having a rectangular cross-sectional structure, and is arranged on both sides of the output waveguide 107.

Output Waveguide 107 and Correction Output Waveguide 10
8 is an output waveguide side end face 1 of the output side slab waveguide 106
It is arranged radially from 15 centers of curvature 116.

FIG. 2 is a principle diagram of the demultiplexing of the optical signal. First, the principle of demultiplexing will be described with reference to FIG. Wavelength λ
Wavelength multiplexed light λ 117 in which N waves of 1 to λ 2 are multiplexed
Is demultiplexed into N output waveguides. WDM light 117 incident on the input waveguide 102
Is propagated through the input waveguide 102 and then diffracted by the input side slab waveguide 104. At this time, the array waveguide side end face 110 is connected to the input waveguide 102 and the input side slab waveguide 1.
Since the connection point 04 is the center of curvature 112, the diffracted wavelength-multiplexed light 117 is incident on the arrayed waveguide diffraction grating 105 with the same phase.

The wavelength multiplexed light 117 incident on each channel waveguide of the arrayed waveguide diffraction grating 105 propagates through each channel waveguide 122 and is incident on the output side slab waveguide 106. However, since the plurality of channel waveguides 122 constituting the array waveguide diffraction grating 105 have different lengths, the phase at each channel waveguide 122 at the array waveguide side end face 113 of the output side slab waveguide 106 is different. Are different. Assuming that the waveguide length difference of the arrayed waveguide diffraction grating 105 is ΔL, the phase φ between adjacent channel waveguides is φ = 2πneΔL / λ (4) where ne is the effective refractive index of the channel waveguide. This equation indicates that the phase between the channel waveguides depends on the wavelength of the wavelength multiplexed light 117. Differentiating the equation (4) with respect to the wavelength λ, δφ = −2πneΔLδλ / λ2 (5), which indicates that there is a proportional relationship between the wavelength dependence δφ of the phase and the wavelength change δλ.

Therefore, the equal phase plane 121 of the wavelength multiplexed light 117 propagating through the array waveguide diffraction grating 105 is inclined with respect to the array waveguide side end face 113 of the output side slab waveguide 106. Array waveguide side end face 1 of each channel waveguide 122 constituting array waveguide diffraction grating 105
Assuming that the interval at 13 is s, the slope δθ of the phase plane with respect to the wavelength difference δλ is as follows from the equation (5): δθ = −tan ⁻¹ ｛ΔLδλ / (sλ)｝ (6) Further, since the phase surface is concave, the wavelength multiplexed light 117 is focused on the output waveguide side end face 115 of the output side slab waveguide 106. Therefore, the output waveguide 10
7 are arranged at an angular interval δθ about the center of curvature 116, the wavelength-division multiplexed light 117 can be demultiplexed.

FIG. 3 shows a method of correcting the center wavelength using the correction output waveguide. Hereinafter, a method of correcting the center wavelength using the correction output waveguide will be described. Wavelength multiplexed light
(Wavelength interval Δλ). When the wavelength-division multiplexed light λ enters the input waveguide, λ1, λ2,.
It is assumed that N is split.

The wavelength multiplexed light 117 incident from the input waveguide 102 propagates through the input side slab waveguide 104 and the arrayed waveguide diffraction grating 105 in the same manner as described above. Further, in the output side slab waveguide 106, the light is propagated in each direction for each wavelength, and is condensed on the output waveguide side end face 115. At this time, according to the equation (6), the light signal whose wavelength is shifted by δλ has a light collecting direction inclined by δθ. Conversely, δθ
If the output waveguide 107 or the correction output waveguide 108 is used, the center wavelength can be corrected by δλ. However, since the output waveguide and the correction output waveguide are arranged discretely, the correction amount of the center wavelength is also discrete. If the angular interval between adjacent waveguides of the output waveguide 107 and the correction output waveguide 108 is Δθout (constant), the output waveguide 107 to be used (the correction output waveguide 10
8 is also shifted by k lines, the corrected center wavelength 119 shifted by kΔλ (k = ± 1, ± 2,...) With respect to the center wavelength 118 before correction can be obtained. .

FIG. 4 shows a method of correcting the center wavelength by the input waveguide 103 for correction. Hereinafter, wavelength multiplexed light is referred to as λ
(Wavelength interval Δλ). When the wavelength-division multiplexed light λ enters the input waveguide 102, λ 1,
It is assumed that λ2,..., λN are split.

Consider a case where wavelength-division multiplexed light is incident on the correction input waveguide 103 inclined by θin with respect to the input waveguide 102. The wavelength-division multiplexed light 117 incident on the input waveguide 103 for correction is input to the input waveguide 103 for correction and the slab waveguide 10 on the input side similarly to the case where the light is input to the input waveguide 102.
4 and is incident on the arrayed waveguide diffraction grating 105. However, the correction input waveguide 103 is the input waveguide 10
It is inclined by θin with respect to 2. Therefore, when the light is incident on the arrayed waveguide diffraction grating 105, the equal phase plane 120 of the wavelength multiplexed light 117 is inclined by θin as compared with the case where the light is incident on the input waveguide 102. Therefore, even when the light is output from the arrayed waveguide diffraction grating 105 to the output side slab waveguide 106, the equal phase plane 121 of the wavelength multiplexed light is
Each of them is inclined by θin as compared with the case where the light enters from 02. That is, the light collecting directions are also inclined by θin.

Here, in the arrayed waveguide diffraction grating,
Assuming that the difference between the angle in the demultiplexing direction and the wavelength difference δλ is δθ, the shift amount θin of the light collecting direction by the correction input waveguide 103 is equivalent to the wavelength shift amount δλin = (δλ / δθ) θin . Therefore, if the correction input waveguide 103 tilted by θin is used, the center wavelength can be corrected by δλin. However, since the input waveguide 102 and the correction input waveguide 103 are disposed discretely, the correction amount of the center wavelength is also discrete. Assuming that the angle interval between the adjacent waveguides of the input waveguide 102 and the correction input waveguide 103 is Δθin (constant), if the correction input waveguide 103 that is m distances from the input waveguide is used, m · ( Δθin / Δθout) · Δλ (8) (m = ± 1, ± 2,...) The center wavelength can be corrected.

As described above, when both the correction input waveguide 103 and the correction output waveguide 108 are used, the correction amount δλ of the center wavelength is: δλ = {k + m · (Δθin / Δθout)} · Δλ (9) (K = ± 1, ± 2,..., M = ± 1, ± 2,...) Where Δθin: the angle between the waveguides of the input waveguide and the input waveguide for correction Δθout: the output waveguide and the output for correction The angle Δλ between the waveguides of the waveguides is the demultiplexing interval of the wavelength multiplexed light.

Other Embodiments and Modifications The optical wavelength multiplexer / demultiplexer of the present invention can be applied not only to those manufactured on a glass substrate but also those manufactured on a semiconductor substrate or the like. In addition, the core, the cladding, and the buffer layer can be applied not only to a glass-based material but also to a material formed using an optically transparent material such as a semiconductor material.

The present invention is also applicable to a plurality of input waveguides, non-equally spaced output waveguides, non-equally spaced correction input waveguides, and non-equally spaced correction output waveguides.

[0036]

In general, the arrayed waveguide grating type optical wavelength multiplexer / demultiplexer is very sensitive to process deviations and the like. In particular, the center wavelength was very sensitive, so the yield was very low.

As described above, if the optical wavelength multiplexer / demultiplexer of the present invention is used, the central wavelength can be corrected, and an incalculable effect can be expected in an optical communication system using wavelength multiplexing.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an optical wavelength multiplexer / demultiplexer according to the present invention.

FIG. 2 is a principle diagram of wavelength demultiplexing of the optical wavelength multiplexer / demultiplexer of the present invention.

FIG. 3 is a principle diagram of center wavelength correction by a correction output waveguide of the optical wavelength multiplexer / demultiplexer of the present invention.

FIG. 4 is a principle diagram of central wavelength correction by a correction input waveguide of the optical wavelength multiplexer / demultiplexer of the present invention.

FIG. 5 is a schematic diagram of a conventional optical wavelength multiplexer / demultiplexer.

6 is a sectional view of the conventional optical wavelength multiplexer / demultiplexer shown in FIG. 5,
5A is a cross-sectional view taken along line AA in FIG. 5, FIG. 5B is a cross-sectional view taken along line BB in FIG. 5, FIG. 5C is a cross-sectional view taken along line CC in FIG.
It is a figure showing D section.

FIG. 7 is a principle diagram of wavelength demultiplexing of a conventional optical wavelength multiplexer / demultiplexer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Substrate 102 Input waveguide 103 Correction input waveguide 104 Input side slab waveguide 105 Array waveguide diffraction grating 106 Output side slab waveguide 107 Output waveguide 108 Correction output waveguide 109 Input waveguide side end face 110 Array waveguide Side end face 111 Center of curvature 112 Center of curvature 113 Array waveguide side end face 114 Center of curvature 115 Output waveguide side end face 116 Center of curvature 117 Wavelength multiplexed light 118 Center wavelength before correction 119 Center wavelength after correction 120 Isophase plane 121 Phase equal plane 122 channel waveguide 201 substrate 202 input waveguide 203 input slab waveguide 204 arrayed waveguide diffraction grating 205 output side slab waveguide 206 output waveguide 207 buffer layer 208 core 209 clad 210 channel waveguide 211 wavelength multiplexed light 212 array Waveguide-side end surface 213 Equal phase surface 214 Array waveguide-side end surface 215 Output waveguide-side end surface 216 Center of curvature 217 Center of curvature

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Naoto Uezuka 5-1-1, Hidaka-cho, Hitachi City, Ibaraki Pref. Opto-System Research Laboratories, Hitachi Cable Ltd. (56) References JP-A-8-211237 (JP, A) JP-A-6-3556 (JP, A) JP-A-2-244105 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/12-6 / 138 G02B 6/28 G02B 6/293

Claims (1)

(57) [Claims] 1. A substrate, a plurality of input waveguides formed on the substrate, an input-side slab waveguide connected to the input waveguide and having a flat plate structure, and the input waveguide , And an output slab waveguide connected to the arrayed waveguide grating, the arrayed waveguide grating including a plurality of channel waveguides having a waveguide length of Li (i = 1, 2, 3,...) If, Bei and a plurality of output waveguides connected to the output side slab waveguide side
And the input waveguide.
One input-side optical fiber for connection to the
Less than the number of output waveguides to connect to the waveguide
Prepare the number of output-side optical fibers and divide them into output-side optical fibers.
So that the center wavelength of the wave to be waved has a desired value.
An input optical fiber is inserted into one of the plurality of input waveguides,
An output optical fiber is connected to any of the plurality of output waveguides.
A method for manufacturing an optical device, wherein the optical devices are connected to each other .