Multichannel dispersion compensation wavelength division multiplexing chip

Abstract

The invention provides a multichannel dispersion compensation wavelength division multiplexing chip. The multichannel dispersion compensation wavelength division multiplexing chip comprises a multi-mode chirp grating auxiliary reverse coupler and a mode demultiplexer, the multi-mode chirp grating auxiliary reverse coupler is connected with an input waveguide of the mode demultiplexer; optical signals with different wavelengths are coupled to different modes through a multi-mode chirp grating auxiliary reverse coupler and dispersion compensation is carried out, the optical signals with different wavelengths in different modes are separated through a mode demultiplexer, and the functions of multi-channel dispersion compensation and wavelength demultiplexing are achieved at the same time. According to the invention, the chirp grating is replaced by the double-waveguide chirp grating-assisted reverse coupler, so that the problem of input and output separation of the traditional chirp grating is solved.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a multi-channel dispersion compensation wavelength division multiplexing chip. Background Art

[0002] Loss, dispersion and nonlinearity are the main factors limiting fiber-optic communication. The invention of erbium-doped fiber amplifiers solved the problem of signal attenuation. Since then, high-speed, long-distance, and large-capacity fiber-optic communication systems have developed rapidly. Dispersion and nonlinear management have become key factors limiting fiber-optic communication systems. In order to prevent four-wave mixing, it is necessary to retain a certain amount of dispersion in the optical fiber to suppress nonlinearity, which limits the application of dispersion-shifted optical fibers with near-zero dispersion in wavelength division multiplexing systems. Retaining a small amount of dispersion and compensating for dispersion has become the main technical solution. Dispersion-compensating optical fibers with negative dispersion are widely used in dispersion compensation because of their large bandwidth characteristics, but the amount of dispersion compensated is small and the required length is long, so longer dispersion-compensating optical fibers are often required for compensation, which increases the loss, size, and nonlinearity of the system. Chirped Bragg fiber gratings use the characteristics of grating reflection to allow signals of different wavelengths to obtain different delays, and have many advantages such as low loss and free bandwidth.

[0003] With the development of integrated photonics, chirped gratings on integrated platforms have been widely studied. The waveguide chirped gratings on the integrated platform have higher integration and more flexible arrangements. However, the Bragg grating input and output are at one port, and an independent optical circulator or on-chip splitter is required to separate the input light and the output light, which increases the difficulty of device integration and causes additional insertion loss. Another problem is that compensation for large bandwidth and high dispersion values ​​often requires a longer grating length. Due to size and loss factors, the grating length is limited and can usually only achieve dispersion compensation of hundreds of ps and less than 10nm. This cannot cover all wavelengths of wavelength division multiplexing, and multiple gratings are usually used to compensate for different channels.

[0004] Patent document CN115941045A (application number: CN202211241260.9) discloses a discrete dispersion compensation device based on a multi-channel micro-ring. The upload waveguide and the download waveguide are arranged in parallel and spaced apart, and there is a multi-channel parallel micro-ring assembly between the upload waveguide and the download waveguide, including n micro-rings arranged in spaced apart directions in the waveguide direction, and there is a delay line on the upload waveguide between two adjacent micro-rings, so that different micro-rings adapt to optical signals of different wavelengths; the dispersion compensation signal is input into the upload waveguide, coupled and transmitted to the download waveguide through each micro-ring in the multi-channel parallel micro-ring assembly, and is divided into n discrete wavelength signals through n micro-rings, and finally output after wavelength division multiplexing and beam combining in the download waveguide. However, the patent does not use a chirped grating-assisted reverse coupler for dual waveguides, cannot replace the chirped grating, and cannot solve the input and output separation problem of the traditional chirped grating. Summary of the invention

[0005] In view of the defects in the prior art, an object of the present invention is to provide a multi-channel dispersion compensation wavelength division multiplexing chip.

[0006] The multi-channel dispersion compensation wavelength division multiplexing chip provided by the present invention comprises a multi-mode chirped grating auxiliary reverse coupler and a mode demultiplexer;

[0007] The multi-mode chirped grating assisted reverse coupler is connected to the input waveguide of the mode demultiplexer;

[0008] Optical signals of different wavelengths are coupled to different modes through a multi-mode chirped grating-assisted reverse coupler and dispersion compensation is performed. Optical signals of different wavelengths in different modes are separated through a mode demultiplexer, which simultaneously plays the role of multi-channel dispersion compensation and wavelength division multiplexing.

[0009] Preferably, the multi-mode chirped grating assisted reverse coupler comprises: a reverse coupling region is formed by two parallel waveguides with a grating structure in the middle, refractive index chirp is achieved by linearly changing the width of the upper waveguide, and grating toe-cut is achieved by changing the spacing between the two waveguides.

[0010] Preferably, the multi-mode chirped grating assisted reverse coupler includes: an upper waveguide is a single-mode waveguide for input, and a lower waveguide is a multi-mode waveguide for output. When the optical signal is reversely coupled from the upper channel to the lower channel, different wavelengths are coupled into different modes of different multi-mode waveguides, and multi-channel dispersion compensation is achieved by mode multiplexing. The number of channels achieved is related to the number of modes supported by the multi-mode waveguide of the lower channel of the multi-mode chirped grating assisted reverse coupler.

[0011] Preferably, the mode demultiplexer adopts a cascaded asymmetric directional coupler structure to couple the optical signal of a specified high-order mode to a specified port, and outputs the optical signal of a different mode from the lower multimode waveguide in the multi-mode chirped grating assisted reverse coupler from different ports, thereby realizing the function of wavelength division multiplexing together with the multi-mode chirped grating assisted reverse coupler.

[0012] Preferably, the optical signal is input through a single-mode waveguide, and when the wavelength λ of the input optical signal c Satisfy the refractive index matching condition: [n effa (z)+n effb (z)+n effbi (z)]Λ=λ c When , the input end of the multi-mode chirped grating auxiliary reverse coupler is reversely coupled to the output end;

[0013] Among them, n effa (z) is the effective refractive index of the single-mode waveguide, n effbi (z) is the effective refractive index of the i-th order mode of the multimode waveguide;

[0014] The waveguide grating is formed by linearly changing the width Λ so that the grating effective refractive index n effa (z) and n effb (z) or Λ changes linearly along the propagation direction z, so that the reflection wavelength at different positions of the grating is different, and the output signal has a delay amount that changes linearly with the wavelength, thus achieving dispersion compensation; the effective refractive index n of different modes in the multimode waveguide effbi Different, the optical signal meets the mode matching condition of reverse coupling at different wavelengths and is coupled into the multimode waveguide and output in different modes;

[0015] The dispersion compensation of a single channel is achieved by chirping the grating. The input waveguide of the multi-mode chirped grating assisted reverse coupler is a multi-mode waveguide. The mode multiplexing enables a single chirped grating assisted reverse coupler to compensate multiple wavelengths and realize multi-channel dispersion compensation.

[0016] Preferably, the waveguide effective refractive index is changed by adjusting the waveguide width to form a refractive index chirp, so that the group delay varies with the wavelength to achieve dispersion compensation; the waveguide coupling coefficient is changed by adjusting the waveguide width to achieve grating toe-cutting to suppress delay jitter and side lobes.

[0017] Preferably, the multimode waveguide is connected to a mode demultiplexer to achieve mode separation, and ultimately achieve single-input multi-output dispersion compensation and mode demultiplexing.

[0018] Preferably, the reversible principle of the optical path is utilized to reverse the input and output of the structure, thereby realizing multi-channel dispersion compensation and mode multiplexing with multiple inputs and a single output.

[0019] Preferably, a mode demultiplexer is not used, and two identical structures are cascaded, with the first stage having single-mode waveguide input and multi-mode output, and the second stage having multi-mode waveguide input and single-mode waveguide output, thereby achieving multi-wavelength dispersion compensation with single input and single output.

[0020] Preferably, the multimode waveguide comprises a rectangular waveguide, and a superstructure is used to adjust the effective refractive index distribution of different modes thereof to adjust the wavelength spacing of the wavelength division multiplexing structure.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention adopts a dual-waveguide chirped grating-assisted reverse coupler to replace the chirped grating, thereby solving the input-output separation problem of the traditional chirped grating and eliminating the need for an optical ring device that is not conducive to integration;

[0023] (2) The present invention utilizes the variation in the spacing of the waveguide to achieve apodization, thereby reducing the difficulty of manufacturing;

[0024] (3) The present invention adopts a mode multiplexing structure, so that the grating can perform dispersion compensation for multiple wavelength channels;

[0025] (4) The present invention can utilize a mode multiplexer / demultiplexer to perform dispersion compensation on a wavelength division multiplexed signal while performing wavelength division multiplexing / demultiplexing at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0027] Figure 1 This is a schematic diagram of Embodiment 1 of the present invention;

[0028] Figure 2 The waveguide cross-section diagram of the four-mode chirped grating assisted reverse coupler of Example 1 of the present invention; the symbols in the figure are: 1-1: input waveguide; 1-2: upper waveguide of the chirped grating assisted reverse coupler; 2-1: output waveguide 1; 2-2: output gradient waveguide 3; 2-3: upper waveguide of TE1-TE0 directional coupler; 2-4: output gradient waveguide 2; 2-5: upper waveguide of TE2-TE0 directional coupler; 2-6: output gradient waveguide 1; 2-7: upper waveguide of TE3-TE0 directional coupler; 2-8: lower waveguide of the chirped grating assisted reverse coupler; 3-1: output waveguide 2; 3-2: lower waveguide of TE1-TE0 directional coupler; 4-1: output waveguide 2; 4-2: lower waveguide of TE2-TE0 directional coupler; 5-1: output waveguide 2; 5-2: lower waveguide of TE3-TE0 directional coupler;

[0029] Figure 3 Schematic diagram of a top view of a waveguide according to Embodiment 1 of the present invention;

[0030] Figure 4 This is a dimensional illustration of Embodiment 1 of the present invention;

[0031] Figure 5 A comparison diagram of the effect of the position of the multimode waveguide etched groove on the four-mode effective refractive index in Example 1 of the present invention;

[0032] Figure 6 (a) to (e) are simulation result diagrams of Example 1 of the present invention;

[0033] Figure 7 This is a schematic diagram of Embodiment 2 of the present invention;

[0034] Figure 8The waveguide cross-section diagram of the 2×2 mode chirped grating assisted reverse coupler of embodiment 2 of the present invention; the symbols in the figure are: 1-1: output waveguide 1; 1-2: lower waveguide of mode demultiplexer 2; 2-1: output waveguide 2; 2-2: upper waveguide of mode demultiplexer 2; 2-3: output gradient waveguide 1; 2-4: lower waveguide 1 of the reverse coupler assisted by the chirped grating; 3-1: input waveguide; 3-2: lower waveguide of TE1-TE0 directional coupler; 4-1: output waveguide 3; 4-3: lower waveguide of TE2-TE0 directional coupler; 4-3: output gradient waveguide 2; 4-4: lower waveguide 2 of the reverse coupler assisted by the chirped grating; 5-1: output waveguide 4; 5-2: lower waveguide of TE1-TE0 directional coupler;

[0035] Fig. 9 is a schematic top view of a waveguide according to Embodiment 2 of the present invention;

[0036] Fig.10 This is a dimensional illustration of Embodiment 2 of the present invention;

[0037] Fig.11 (a) to (e) are simulation result diagrams of Example 2 of the present invention. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0039] Example 1

[0040] like Figure 1 and Figure 2 As shown, the present invention provides a four-mode four-channel chirped grating assisted reverse coupler type dispersion compensator, which mainly includes a four-mode chirped grating assisted reverse coupler and a four-mode demultiplexer.

[0041] The four-mode chirped grating assisted reverse coupler realizes four-channel dispersion compensation and is composed of two adjacent parallel waveguides 1-2 and 2-8. The upper waveguide 1-2 of the four-mode chirped grating assisted reverse coupler is a single-mode waveguide, and the lower waveguide 2-8 is a multimode waveguide supporting four modes.

[0042] The optical signal to be processed enters the uplink waveguide 1-2 of the chirped grating assisted reverse coupler type dispersion compensator from the input waveguide 1-1. According to the mode matching condition, the central wavelength of the reverse coupling is related to the effective refractive index of the waveguide: ci =[n effa (z)+neffbi The signals of different wavelengths λ1, λ2, λ3, and λ4 are respectively reversely coupled to the four different modes TE0, TE1, TE2, and TE3 of the lower waveguide 2-8, thereby realizing multi-channel dispersion compensation of mode division multiplexing.

[0043] Waveguide size reference Figure 3 , Figure 4 .

[0044] Figure 3 In, H1=220nm, H2=70nm, A=200nm, B=510nm, Wa=470nm, Wb=2350nm, Wg=75nm, G=200nm;

[0045] Figure 4 Medium: Wa1=520nm, Wa2=500nm, Wb1=Wb2=2350nm, Wg=75nm, G=225nm, p=303.5nm.

[0046] The specific details are as follows:

[0047] 1. Multimode waveguide design

[0048] The grating-assisted reverse coupler consists of two waveguides. The upper waveguide 1-2 is a single-mode tapered waveguide. The lower waveguide 2-8 is a multimode waveguide. The inner side of the multimode waveguide has a grating structure to achieve reverse coupling. According to the mode matching condition, the central wavelength of the reverse coupling is related to the effective refractive index of the waveguide: λ c =[n effa (z)+n effbi (z)]Λ.

[0049] In order to adjust the effective refractive index of each mode, the different distribution of each mode in the waveguide is used here, and a groove with a depth of H2 = 70nm and a width of 200nm is engraved on the multimode waveguide. At 1550nm, the change of the effective refractive index of the multimode waveguide with the width of the groove position B is shown as follows Figure 5 To adjust the wavelength interval to be the same, select B = 610nm.

[0050] 2. Waveguide spacing design

[0051] Since the length of the grating is not infinite, the Fourier transform of the grating with a rectangular function is usually a sinc function, resulting in side lobes and group delay jitter in the transmission spectrum. The widespread use of apodization suppresses side lobes and ripples. Since the reverse coupling coefficient of the waveguide is related to the waveguide spacing, the closer the waveguide distance, the greater the coupling coefficient. Asymmetric apodization is achieved by changing the spacing G between the two waveguides. The function of the waveguide spacing G with respect to the position z is as follows:

[0052]

[0053] L is the total length of the grating, Gmin is the minimum spacing between the two waveguides, and the coefficient a and the constant H determine the curvature and the maximum spacing, which is the toe-cutting strength.

[0054] 3. Refractive index chirp design

[0055] The chirp of the effective refractive index, here the linear chirp of the refractive index is adopted, so that the width of the single-mode waveguide 1-2 changes linearly with z: Wa1=490nm, Wa2=470nm.

[0056] The four-mode mode demultiplexer is used to separate the four-mode optical signal. The cascaded asymmetric directional coupler is used to gradually separate the modes in the grating coupler from high order to low order. The TE3, TE2, and TE0 modes are separated and converted into the fundamental mode by three asymmetric directional couplers. The principle is that when the effective refractive index of the high-order mode in the multimode waveguide is close to the effective refractive index of the fundamental mode of the single-mode waveguide, the energy of the high-order mode will be coupled to the fundamental mode, and most of the energy can be forced to transfer through the length and tapered design of the waveguide.

[0057] This embodiment uses Lumerical finite-difference time-domain method (FDTD) to calculate and analyze the grating with 2000 cycles. The results are as follows: Figure 6 As shown, Figure (a) is the reflection spectrum of the four channels of the chirped grating-assisted reverse coupler, and Figures (b), (c), (d), and (e) are the group delay curves of output ports 1, 2, 3, and 4, respectively. As shown in Figure (a), the bandwidths of output ports 4, 1, 2, and 3 at 1530nm, 1550nm, 1570nm, and 1590nm are 4nm, 2.8nm, 3.2nm, and 2.4nm, the insertion loss is 4.2dB, 1.2dB, 2.0dB, and 0.14dB, and the crosstalk is less than -20dB. Figures (b), (c), (d), and (e) show that the maximum dispersion of the four channels is -7.1ps / nm, -6.2ps / nm, -6.9ps / nm, and -6.0ps / nm, and the average dispersion is 1.6ps / nm, -2.5ps / nm, -2.1ps / nm, and -2.8ps / nm.

[0058] Example 2

[0059] like Figure 7 and Figure 8 As shown, the present invention provides a 2×2 mode four-channel chirped grating assisted reverse coupler type dispersion compensator, which mainly includes a 2×2 mode chirped grating assisted reverse coupler and two mode demultiplexers.

[0060] The 2×2 mode chirped grating assisted reverse coupler is composed of two 2-mode chirped grating assisted reverse couplers of different periods. The two chirped grating assisted reverse couplers share an input waveguide 3-2, so that the input optical signal is coupled to the TE1 and TE0 modes of the lower waveguide 2-4 at the central waveguides of λ2 and λ4, the TE0 mode signal is directly output from the 2-1 port, and the TE1 mode is converted into the TE0 signal via the mode converter 1 and output from the 1-1 port; the optical signal is coupled to the TE1 and TE0 modes of the lower waveguide 4-4 at the λ1 and λ3 central wavelengths, the TE0 mode signal is directly output from the 4-1 port, and the TE1 mode is converted into the TE0 signal via the mode converter 1 and output from the 5-1 port. The method of grating refractive index chirping and toe cutting is the same as that in Example 1.

[0061] Size reference Fig. 9 , Fig.10 .

[0062] Fig.10 Center: Wa1=520nm, Wa2=500nm, Wb1=Wb2=1250nm, Wc1=Wc2=1240nm, Wg=150nm, G=150nm, p1=300.5nm, p2=295nm.

[0063] This embodiment uses Lumerical finite-difference time-domain method (FDTD) to calculate and analyze the grating with 2000 cycles. The results are as follows: Fig.11 As shown, Figure (a) is the reflection spectrum of the four channels of the chirped grating-assisted reverse coupler, and Figures (b), (c), (d), and (e) are the group delay curves of output ports 4, 1, 2, and 3, respectively. As shown in Figure (a), the bandwidths of output ports 4, 1, 2, and 3 at 1530nm, 1550nm, 1570nm, and 1590nm are 2.4nm, 2.4nm, 1.8nm, and 1.8nm, the insertion loss is less than 2dB, and the crosstalk is less than -20dB. Figures (b), (c), (d), and (e) show that the maximum dispersion of the four channels is -10.2ps / nm, -6.4ps / nm, -9.8ps / nm, and -3.6ps / nm, and the average dispersion is -3.6ps / nm, -3.4ps / nm, -3.9ps / nm, and -3.5ps / nm.

[0064] In summary, the multi-mode multi-channel chirped grating-assisted reverse coupler type optical dispersion delay line provided by the present invention can realize dispersion compensation and wavelength division multiplexing for optical signal inputs of multiple wavelength channels. It has more potential in wavelength division multiplexing systems than conventional single-channel signals, can provide high dispersion values ​​in a compact chip size, and can be better applied to integrated dispersion compensation, optical caching, and optical true delay networks.

[0065] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0066] Those skilled in the art know that, in addition to implementing the system, device and its various modules provided by the present invention in a purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers and embedded microcontrollers by logically programming the method steps. Therefore, the system, device and its various modules provided by the present invention can be considered as a hardware component, and the modules included therein for implementing various programs can also be considered as structures within the hardware component; the modules for implementing various functions can also be considered as both software programs for implementing the method and structures within the hardware component.

[0067] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A multi-channel dispersion compensation wavelength division multiplexing chip, It is characterized in that including a multi-mode chirped grating assisted reverse coupler and a mode demultiplexer; The multi-mode chirped grating assisted reverse coupler is connected to the input waveguide of the mode demultiplexer; Optical signals of different wavelengths are coupled to different modes through a multi-mode chirped grating-assisted reverse coupler and dispersion compensation is performed. Optical signals of different wavelengths in different modes are separated through a mode demultiplexer, which simultaneously plays the role of multi-channel dispersion compensation and wavelength division multiplexing.

2. The multi-channel dispersion compensation wavelength division multiplexing chip according to claim 1, It is characterized in that The multi-mode chirped grating assisted reverse coupler comprises: a reverse coupling region is formed by two parallel waveguides with a grating structure in the middle, refractive index chirping is achieved by linearly changing the width of the upper waveguide, and grating toe cutting is achieved by changing the spacing between the two waveguides.

3. The multi-channel dispersion compensation wavelength division multiplexing chip according to claim 2, It is characterized in that The multi-mode chirped grating assisted reverse coupler comprises: an upper waveguide is a single-mode waveguide for input, and a lower waveguide is a multi-mode waveguide for output. When an optical signal is reversely coupled from the upper channel to the lower channel, different wavelengths are coupled into different modes of different multi-mode waveguides, and multi-channel dispersion compensation is achieved by mode multiplexing. The number of channels achieved is related to the number of modes supported by the multi-mode waveguide of the lower channel of the multi-mode chirped grating assisted reverse coupler.

4. The multi-channel dispersion compensation wavelength division multiplexing chip according to claim 3, It is characterized in that The mode demultiplexer adopts a cascaded asymmetric directional coupler structure to couple the optical signal of the specified high-order mode to the specified port, outputs the optical signal of the different mode from the lower multimode waveguide in the multimode chirped grating auxiliary reverse coupler from different ports, and realizes the function of wavelength division multiplexing together with the multimode chirped grating auxiliary reverse coupler.

5. The multi-channel dispersion compensation wavelength division multiplexing chip according to claim 3, It is characterized in that The optical signal is input from a single-mode waveguide. When the wavelength of the input optical signal is c Satisfy the refractive index matching condition: [n effa (z)+n effb (z)+n effbi (z)]Λ=λ c When , the input end of the multi-mode chirped grating auxiliary reverse coupler is reversely coupled to the output end; Among them, n effa (z) is the effective refractive index of the single-mode waveguide, n effbi (z) is the effective refractive index of the i-th order mode of the multimode waveguide; The waveguide grating is formed by linearly changing the width Λ so that the grating effective refractive index n effa (z) and n effb (z) or Λ changes linearly along the propagation direction z, so that the reflection wavelength at different positions of the grating is different, and the output signal has a delay amount that changes linearly with the wavelength, thus achieving dispersion compensation; the effective refractive index n of different modes in the multimode waveguide effbi Different, the optical signal meets the mode matching condition of reverse coupling at different wavelengths and is coupled into the multimode waveguide and output in different modes; The dispersion compensation of a single channel is achieved by chirping the grating. The input waveguide of the multi-mode chirped grating assisted reverse coupler is a multi-mode waveguide. The mode multiplexing enables a single chirped grating assisted reverse coupler to compensate multiple wavelengths and realize multi-channel dispersion compensation.

6. The multi-channel dispersion compensation wavelength division multiplexing chip according to claim 5, It is characterized in that By adjusting the waveguide width, the effective refractive index of the waveguide is changed to form a refractive index chirp, so that the group delay changes with the wavelength and dispersion compensation is achieved; by adjusting the waveguide width, the waveguide coupling coefficient is changed and grating toe-cut is achieved to suppress delay jitter and side lobes.

7. The multi-channel dispersion compensation wavelength division multiplexing chip according to claim 3, It is characterized in that The multimode waveguide is connected to the mode demultiplexer to achieve mode separation, and ultimately achieve single-input multi-output dispersion compensation and mode demultiplexing.

8. The multi-channel dispersion compensation wavelength division multiplexing chip according to claim 1, It is characterized in that By utilizing the reversible principle of the optical path, the input and output of the structure are reversed to achieve multi-channel dispersion compensation and mode multiplexing with multiple inputs and a single output.

9. The multi-channel dispersion compensation wavelength division multiplexing chip according to claim 3, It is characterized in that Instead of using a mode demultiplexer, two identical structures are cascaded, with the first stage having single-mode waveguide input and multi-mode output, and the second stage having multi-mode waveguide input and single-mode waveguide output, thereby achieving multi-wavelength dispersion compensation with single input and single output.

10. The multi-channel dispersion compensation wavelength division multiplexing chip according to claim 3, It is characterized in that The multimode waveguide includes a rectangular waveguide, and a superstructure is used to adjust the effective refractive index distribution of different modes of the multimode waveguide to adjust the wavelength spacing of the wavelength division multiplexing structure.

Images