JP4083045B2 - Center wavelength control method of wavelength filter for series coupled ring resonator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application is intended to relate to the central wavelength control method of the series coupled ring resonators wavelength filter.
[0002]
[Prior art]
Conventionally, for example, as shown in FIG. 1, a ring resonator (a kind of add / drop filter) serving as an optical coupling portion between an input side optical waveguide (1) and an output side optical waveguide (2) ( A micro-ring resonator wavelength filter having a structure in which (3) is arranged (also referred to as “ring waveguide”) is known (see Patent Document 1).
[0003]
In this wavelength filter, a tunable wavelength filter can be realized by controlling the equivalent refractive index of the ring resonator (3) from the outside using a thermo-optic effect, an electro-optic effect, a magneto-optic effect, and the like. Specifically, for example, when the thermo-optic effect is used, as illustrated in FIG. 2, an electrode to be a heater (4) is formed on the filter, and the ring resonator (3) is heated by the heater (4). Then, central wavelength control is performed. The center wavelength is obtained by λ = (2πR · n _eq ) / N [R = ring radius, n _eq = equivalent refractive index, N = resonance order].
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-298215
[Problems to be solved by the invention]
However, when the center wavelength of the filter is moved from one wavelength channel to another wavelength channel, the optical signal of the moving channel is temporarily transmitted to the output side optical waveguide (2) as illustrated in FIG. Problem arises.
[0006]
Therefore, in view of the circumstances as described above, the invention of this application provides a center wavelength control method for a series coupled ring resonator wavelength filter capable of preventing signal transmission during wavelength shift.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the invention of this application is firstly a series-coupled ring resonance in which two or more ring resonators are coupled to each other between an input-side optical waveguide and an output-side optical waveguide. In the case of a series coupled ring resonator wavelength filter in which two or more ring resonators are coupled to each other between an input side optical waveguide and an output side optical waveguide , the center wavelength of each ring resonator is set to a certain channel. When moving from the center wavelength of the ring resonator to the center wavelength of another desired channel, the center wavelength of each ring resonator is individually set so that the center wavelength of each ring resonator is different at the same time during the movement of the center wavelength. To block the output to the output side optical waveguide of the wavelength channel other than the center wavelength of the target channel, and each ring in the final stage of movement All of the center wavelength of the acoustic transducer to match the center wavelength control method of the series coupled ring resonators wavelength filter, characterized in that for outputting a wavelength channels having center wavelengths of other channels of interest to an output side optical waveguide provide.
[0008]
Second, as the series coupled ring resonator wavelength filter, the input-side optical waveguide and the output-side optical waveguide intersect each other, and the ring resonators are stacked at the intersection. A center wavelength control method for a series coupled ring resonator wavelength filter is provided.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
According to the invention of this application having the above-described features, for example, as illustrated in FIG. 4, two or more ring resonators are provided between the input-side optical waveguide (1) and the output-side optical waveguide (2). (3) are coupled to each other to form a series coupled ring resonator wavelength filter, in which the drop wavelength output to the output side optical waveguide (2) is set separately from the center wavelength of each ring resonator (3). In the process of wavelength control, another wavelength channel that is not intended for output is output to the output-side optical waveguide (2) without being output to the output-side optical waveguide (2). By newly outputting in 2), it is possible to reduce the filter transmittance in the middle of the wavelength shift to a negligible level. In other words, the filter characteristics of the ring resonators (3) are erased before the center wavelength is moved, and a switching characteristic is obtained such that the filter characteristics are output again after the center wavelength is moved. As a result, filter characteristics can be produced only when the center wavelengths match, and signal transmission during wavelength shift can be suppressed, and the change from wavelength λ _n to λ _{n + 2} does not pass through λ _{n + 1.} Will be able to do directly.
[0010]
In one embodiment of FIG. 4, more specifically, an input side optical waveguide (1) having an input port and a through port and an output side optical waveguide (2) having an add port and a drop port intersect with each other in the lower cladding. The three ring resonators (3) (# 1, # 2, # 3) are arranged at the intersection, and the # 1 ring resonator (3) is provided on the input side optical waveguide (1). ), A three-stage series coupling in which a # 3 ring resonator (3) is stacked on the output side optical waveguide (2), and a # 2 ring resonator (3) is stacked between the # 1 and # 3 It has become. In FIG. 4, the stacked structure is such that # 1 and # 3 overlap each other above # 2, but, for example, # 2 may be positioned on the upper side, and the ring resonators (3) and The lamination position of the input side optical waveguide (1) and the output side optical waveguide (2) is not particularly limited. Here, the ring resonator (3) coupled in three stages in this way is referred to as a “triple ring resonator”.
[0011]
Then, the center wavelength of the triple ring resonator, that is, the resonance wavelength may be moved separately. At this time, for example, it is moved sequentially from # 1 to # 3, that is, from the input side to the drop side. Such movement is possible by external control using, for example, a thermo-optic effect, an electro-optic effect, a magneto-optic effect, or the like.
[0012]
Needless to say, the number of ring resonators (3) is not limited to three, but may be two or more multiple series coupling structures.
[0013]
【Example】
[Example 1]
In accordance with the invention of this application, a simulation was performed in which the filter center wavelength initially dropped on channel 1 was moved to channel 12. FIG. 5 shows the analysis result. The graph on the right side of FIG. 5 shows the movement pattern of the center wavelength of each ring used in this simulation, and the graph on the left side shows the change in the transmission spectrum as the simulation result. Is shown.
[0014]
More specifically, in this simulation, it is assumed that there is a triple ring resonator in which each center wavelength is matched in the channel 1 band, and when the center wavelength is moved to the channel 12 band, it is between them. In order to reduce crosstalk in the region, the center wavelength is moved to the band of the channel 12 in order from the # 1 ring to the # 3 ring.
[0015]
As can be seen from FIG. 5, the filter transmittance is suppressed to −30 dB or less in the band between the channel 1 and the channel 12.
[0016]
Therefore, a non-blocking type tunable wavelength filter can be realized.
[0017]
[Example 2]
As a result of a simulation of moving from channel 1 to channel 3 under the same conditions, it was found that a non-blocking tunable wavelength filter in which the crosstalk between them was suppressed to -30 dB or less as shown in FIG. .
[0018]
Of course, the invention of this application is not limited to the above-described embodiments and examples, and various aspects are possible for details.
[0019]
【The invention's effect】
As described above in detail, the invention of this application provides a center wavelength control method for a series coupled ring resonator wavelength filter capable of preventing signal transmission during wavelength shift.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a conventional multilayer microring resonator wavelength filter.
FIG. 2 is a perspective view exemplifying a tunable wavelength filter when the center wavelength is controlled by a thermo-optic effect in a conventional multilayer microring resonator wavelength filter.
FIG. 3 is a diagram for explaining a conventional problem and shows signal transmission during wavelength shift.
FIG. 4 is a perspective view showing an embodiment of the invention of this application.
FIG. 5 is a diagram showing an embodiment of the invention of this application.
FIG. 6 is a diagram showing another embodiment of the invention of this application.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Input side optical waveguide 2 Output side optical waveguide 3 Ring resonator 4 Heater

Claims (2)

In a series-coupled ring resonator wavelength filter in which two or more ring resonators are coupled to each other between an input side optical waveguide and an output side optical waveguide , the center wavelength of each ring resonator is determined from the center wavelength of a certain channel. By moving the center wavelength of each ring resonator individually so that the center wavelength of each ring resonator is different at the same time during the movement of the center wavelength. , Blocking the output of the wavelength channel other than the center wavelength of the target channel to the output side optical waveguide, and matching all the center wavelengths of each ring resonator in the final stage of movement, and the center of another target channel A center wavelength control method for a series coupled ring resonator wavelength filter , wherein a wavelength channel having a wavelength is output to an output optical waveguide . The series-coupled ring resonator wavelength filter is characterized in that the input-side optical waveguide and the output-side optical waveguide intersect with each other, and the ring resonators are stacked at the intersection. The center wavelength control method of the series coupled ring resonator wavelength filter according to claim 1 .

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