A multi-channel silicon-based wavelength division multiplexing 90-degree optical mixing chip

Abstract

The present invention discloses a multi-channel silicon-based wavelength division multiplexing 90-degree optical mixer chip. The silicon-based wavelength division multiplexing 90-degree optical mixer chip includes: a signal light input waveguide, a local oscillator light input waveguide, a 90-degree optical mixer, four arrayed waveguide gratings (AWGs), and an output waveguide. Heating electrodes are provided on both the 90-degree optical mixer and the four AWGs. The signal light and the local oscillator light are coherently mixed in the 90-degree optical mixer to form a set of in-phase signals and a set of quadrature signals. The in-phase signal output terminals of the 90-degree optical mixer are respectively connected to the input terminals of AWG1 and AWG4, and the quadrature signal output terminals are respectively connected to the input terminals of AWG2 and AWG3. The output waveguides of the four AWGs are coupled to an optical fiber array. Based on the 90-degree optical mixer, the arrayed waveguide grating, and the thermal phase shifter, the present invention realizes wavelength division multiplexing of the 90-degree mixed signals, and has the advantages of low phase imbalance, small insertion loss, adjustable working wavelength, etc., and can perform coherent demodulation on data modulated by means such as QPSK and QAM.

Description

Technical Field

[0001] The present invention relates to the field of optical communication, and particularly to a multi-channel silicon-based wavelength division multiplexing 90-degree optical mixer chip. Background Art

[0002] With the substantial increase in data traffic brought about by video streaming, artificial intelligence, and data cloud service applications, backbone network devices are bound to support higher-speed and larger-bandwidth long-distance transmission. In recent years, coherent optical communication technology has received extensive attention. Compared with traditional communication transmission systems, coherent optical communication systems have higher spectral efficiency and receiver sensitivity, and have become the key technology to solve the data transmission bottleneck. As an important component of coherent optical communication systems, 90-degree optical mixers have been widely deployed in long-haul coherent optical communication networks using modulation methods such as quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM). Optical multiplexing technology refers to the technology of improving data transmission capacity and efficiency by simultaneously transmitting different-dimensional signals in a fiber optic transmission system, including dimensions such as polarization, mode, and wavelength. Introducing optical multiplexing technology into coherent optical communication networks can multiply the capacity of transmitted optical signals and further improve data transmission efficiency.

[0003] In a coherent optical communication receiving system, the signal light and the local oscillator light are subjected to 90-degree mixing through a 90-degree optical mixer to output an in-phase signal and a quadrature signal. The in-phase signal and the quadrature signal are respectively subjected to photoelectric conversion through a balanced photodetector and differential amplification, and then sampled and quantized by an analog-to-digital converter (ADC). Finally, the digital signal processor (DSP) processes the discrete digital sequence after sampling and quantization, thereby realizing the functions of signal detection and electrical signal amplification.

[0004] Currently, widely used optical multiplexing methods include polarization division multiplexing, mode division multiplexing, and wavelength division multiplexing, etc. In a polarization division multiplexing coherent receiving system, an optical signal is divided into two orthogonally polarized optical signals by a polarization beam splitter, and the two polarized optical signals are respectively mixed with a local oscillator light to double the capacity of the transmitted optical signal. A mode division multiplexing coherent receiving system refers to using a mode demultiplexer to separate different modes in the signal light, and then mixing the signal lights of different modes with the local oscillator light at 90-degree optical mixing. Its transmission capacity is related to the number of modes that the mode demultiplexer can demultiplex, usually less than 10. Currently, the most widely used and mature optical multiplexing technology is wavelength division multiplexing technology. Coarse wavelength division multiplexing (CWDM) can transmit up to 18 wavelengths in the spectral grid from 1271 nm to 1611 nm at most, while dense wavelength division multiplexing (DWDM) can carry 40, 80, or even up to 160 wavelengths, and its multiplexing ability far exceeds that of polarization multiplexing and mode division multiplexing technologies. Using wavelength division multiplexing technology is an inevitable trend in the development of ultra-high-capacity communication systems. The combination of coherent detection technology and WDM systems is the preferred method to achieve a high-speed coherent optical transmission system of 100 Gb / s and above per channel. This technology can also be applied to microwave photonic channelized receivers. Summary of the Invention

[0005] To solve the above problems and further improve the information transmission capacity, the present invention provides a multi-channel wavelength division multiplexing 90-degree optical mixing chip, which can not only reduce the phase imbalance between the in-phase signal and the quadrature signal output by the 90-degree optical mixer through thermal tuning, but also adjust the central wavelength of the output channels of the AWG to meet the requirements of different WDM systems.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A silicon-based wavelength division multiplexing 90-degree optical mixing chip includes a signal light input waveguide, a local oscillator light input waveguide, a 90-degree optical mixer, four arrayed waveguide gratings, and an output waveguide. The 90-degree optical mixer and the four AWGs are all provided with heating electrodes. The signal light and the local oscillator light are coherently mixed in the 90-degree optical mixer to form two in-phase signals and two quadrature signals. The two in-phase signal output ends of the 90-degree optical mixer are respectively connected to the input ends of AWG1 and AWG4, and the two quadrature signal output ends are respectively connected to the input ends of AWG2 and AWG3. The output waveguides of the four AWGs are coupled with an optical fiber array for output.

[0008] Optionally, the 90-degree optical mixer includes a signal light input waveguide, a local oscillator light input waveguide, a top 1×2 MMI, two 2×2 MMIs on the left and right sides, a bottom 2×2 MMI, a 4-way 90-degree bent waveguide connecting the 4 MMIs, and four output waveguides, where a heating electrode is covered above the 4-way 90-degree bent waveguide; the local oscillator light input waveguide is coupled to the top 1×2 MMI, the signal light input waveguide is coupled to the bottom 2×2 MMI, and the signal light and the local oscillator light are input to the 2×2 MMIs on the left and right sides through the 4-way 90-degree bent waveguide, so that the signal light and the local oscillator light are mixed in the multimode interference regions of the 2×2 MMIs on both sides, and the mixed optical signals are respectively led out to the I-channel output waveguide and the Q-channel output waveguide. A heating electrode is provided at the 4-way 90-degree bent waveguide, and the phase imbalance between the I-channel and the Q-channel is reduced through thermal tuning, thereby improving the image rejection ratio, enhancing the quality of the demodulated signal, avoiding the use of a more expensive DSP for phase compensation, and reducing costs.

[0009] Optionally, the 2×2 MMI multimode interference region is optimized. The contour structures at both ends of the traditional rectangular multimode interference region are optimized to be parabolic, aiming to suppress the reflections on the relatively sharp input / output interfaces at the edges of the MMI, thereby reducing unnecessary energy losses, and at the same time achieving a good balance between the insertion loss and the power imbalance of the MMI.

[0010] Optionally, each of the 4-way 90-degree bent waveguides is composed of 2 non-linear bent tapers, which gradually change from 0.5 μm wide to 2 μm wide uniformly and then back to 0.5 μm wide uniformly. By using the non-linear taper with a gradually changing width, the structure has higher robustness to the manufacturing process, reduces the phase error caused by manufacturing deviations, thereby enhancing the image rejection effect, improving the quality of the demodulated signal, avoiding the use of a more expensive DSP for phase compensation, and reducing costs.

[0011] Optionally, the AWG includes an input channel waveguide, an input coupler, an array waveguide, an output coupler, and an output channel waveguide. The input, output channel waveguides and the array waveguide of the AWG are all strip waveguides, and the FPR is a planar waveguide. The array waveguide region is covered with a heating electrode, and the wavelengths of the output channels of the AWG are made to meet the requirements of the WDM system through thermal tuning.

[0012] Optionally, the AWG input coupler includes an input channel taper, an FPR, and an array waveguide taper. The FPR consists of a Rowland circle and a partial grating circle. The radius of the grating circle is 222.46 μm, and the radius of the Rowland circle is half of the radius of the grating circle. Without changing the diffraction order, the large-radius grating circle can increase the output waveguide spacing and effectively reduce crosstalk between channels. The input channel taper is located on one side of the Rowland circle, and the array waveguide tapers are equally spaced on the circumference of the grating circle, and their extension lines intersect at the center input channel (the center of the grating circle); the array waveguide tapers are connected to the array waveguide, and the array waveguide is designed as a multimode waveguide with a width of 2 μm to reduce the phase error caused by process differences, reduce losses, and improve the smoothness of the output spectrum.

[0013] Optionally, the output coupler includes an array waveguide taper, an FPR, and an output channel taper. The FPR consists of a Rowland circle and a partial grating circle. The radius of the grating circle is 222.46 μm, and the radius of the Rowland circle is half of the radius of the grating circle. Without changing the diffraction order, the large-radius grating circle can increase the output waveguide spacing and effectively reduce crosstalk between channels. The array waveguide tapers are equally spaced on the circumference of the grating circle, and their extension lines intersect at the center output channel (the center of the grating circle), and the output channel tapers are equally spaced on the circumference of the Rowland circle; the array waveguide tapers are connected to the array waveguide, and the array waveguide is designed as a multimode waveguide with a width of 2 μm to reduce the phase error caused by process differences, reduce losses, and improve the smoothness of the output spectrum.

[0014] Optionally, the array waveguide is designed as a multimode waveguide with a width of 2 μm to improve process tolerance, and the wiring method is a saddle-shaped structure, which is more compact than the "Z" - shaped structure. Each array waveguide consists of a straight waveguide, two Euler bent waveguides tangent to it, and two arc bent waveguides at both ends. The Euler bent waveguides are used to reduce the insertion loss. The length difference between adjacent array waveguides is introduced in the straight waveguide part.

[0015] Optionally, using the thermo - optic effect, the center wavelength of the AWG output channels is changed by heating the entire array waveguide region through a thermal electrode to meet the requirements of the WDM system. The AWG heating electrode can be composed of two "serpentine arrangement" electrodes with a common cathode in parallel. While ensuring a sufficiently large resistance value, it covers a larger heating area, has a better heating effect, and can reduce the voltage required for heating.

[0016] Compared with the prior art, the advantages of the present invention are as follows:

[0017] 1. Optimize the traditional rectangular MMI multimode interference region into a parabolic shape, reducing the imbalance and loss.

[0018] 2. In the 90-degree optical mixer, the curved waveguide uses a non-linear taper with a gradually changing width, which improves the tolerance to manufacturing process errors.

[0019] 3. Heating electrodes are arranged at the four-way curved waveguide of the 90-degree optical mixer. By using the thermo-optic effect to change the optical path of one path, the output phase characteristics of the 90-degree optical mixer are tuned to further reduce the phase error.

[0020] 4. The designed AWG uses a large-radius grating circle, Euler curved waveguides, and a multi-mode array waveguide, and has characteristics such as low inter-channel crosstalk, low loss, and smooth output spectral lines.

[0021] 5. "Snake-shaped" arranged heating electrodes are covered in the AWG array waveguide region. By heating the array waveguide region and using the thermo-optic effect, the central wavelength of the AWG output channel can be adjusted to meet the requirements of different WDM systems.

[0022] 6. The multi-channel silicon-based wavelength division multiplexing 90-degree optical mixer chip designed by combining a 90-degree optical mixer and an AWG has a high process tolerance and extremely low power consumption compared with traditional discrete devices, and can be used in devices such as microwave photonic channelized receivers and high-speed coherent optical modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of the multi-channel silicon-based wavelength division multiplexing 90-degree optical mixer chip of the present invention.

[0024] Figure 2 It is a schematic structural diagram of the 90-degree optical mixer of the present invention.

[0025] Figure 3 It is a schematic structural diagram of the 2×2 MMI of the present invention.

[0026] Figure 4 It is a schematic structural diagram of the AWG of the present invention.

[0027] Figure 5 It is the phase error of the 90-degree optical mixer.

[0028] Figure 6 It is the transmission spectrum of the AWG.

[0029] Figure 7 (a) QPSK signal IQ modulation combined wave spectrum, 7(b) QPSK signal IQ modulation spectrum at the central wavelength of 1.55 μm.

[0030] Figure 8 (a) QAM signal IQ modulation combined wave spectrum, 8(b) QAM signal IQ modulation spectrum at the central wavelength of 1.55 μm.

[0031] Figure 9(a) QPSK signal constellation diagram at the center wavelength of 1.55 μm of the channel, and (b) eye diagram of the QPSK signal at the center wavelength of 1.55 μm of the channel,

[0032] Figure 10 (a) QAM signal constellation diagram at the center wavelength of 1.55 μm of the channel, and (b) eye diagram of the QAM signal at the center wavelength of 1.55 μm of the channel.

[0033] Figure 1 Description of the reference numerals of the structural elements:

[0034] 10 90-degree optical mixer,

[0035] 101 Signal optical input waveguide,

[0036] 102 Local oscillator optical input waveguide,

[0037] 103 Positive output terminal of the in-phase signal,

[0038] 104 Positive output terminal of the quadrature signal,

[0039] 105 Negative output terminal of the quadrature signal,

[0040] 106 Negative output terminal of the in-phase signal,

[0041] 20 First AWG,

[0042] 201 Output waveguide array of the first AWG,

[0043] 30 Second AWG,

[0044] 301 Output waveguide array of the second AWG,

[0045] 40 Third AWG,

[0046] 401 Output waveguide array of the third AWG,

[0047] 50 Fourth AWG,

[0048] 501 Output waveguide array of the fourth AWG,

[0049] Figure 2 Description of the reference numerals of the structural elements:

[0050] 60 Input 1×2 MMI,

[0051] 601 Signal optical input port,

[0052] 70 First 2×2 MMI,

[0053] 701 Positive output terminal of the quadrature signal,

[0054] Negative output terminal of the 702 orthogonal signal

[0055] 71 The second 2×2 MMI

[0056] 711 Signal optical input port

[0057] 72 The third 2×2 MMI

[0058] 721 Positive output terminal of the in-phase signal

[0059] 722 Negative output terminal of the in-phase signal

[0060] 80 90-degree bent waveguide

[0061] 90 2×2 MMI multimode interference region structure

[0062] 91 AWG input terminal

[0063] 92 AWG input coupler

[0064] 93 Array waveguide input terminal

[0065] 94 Array waveguide

[0066] 95 Array waveguide output terminal

[0067] 96 AWG output coupler

[0068] 97 AWG output terminal Detailed implementation manners

[0069] To deepen the understanding of the present invention, the following will give a detailed description of this embodiment with reference to the accompanying drawings. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0070] When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views showing the device structure will be enlarged locally in a non-general proportion, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention here. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0071] It should be noted that the drawings provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and ratios of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0072] Example 1: Refer to Figure 1 , a multi-channel silicon-based wavelength division multiplexing 90-degree optical mixing chip. The schematic diagram of the chip structure is as shown in Figure 1 . The wavelength division multiplexing 90-degree optical mixing chip is composed of a signal light input waveguide 101, a local oscillator light input waveguide 102, a 90-degree optical mixer 10, four AWGs (20, 30, 40, 50), and an output waveguide array (201, 301, 401, 501). The 90-degree optical mixer and the four AWGs are all provided with heating electrodes. The signal light and the local oscillator light are coherently mixed in the 90-degree optical mixer 10 to form a set of in-phase signals and a set of quadrature signals. The in-phase signal output terminals of the 90-degree optical mixer are respectively connected to the input terminals of AWG20 and AWG50, and the quadrature signal output terminals are respectively connected to the input terminals of AWG30 and AWG40. The optical signals with different wavelengths are output from different ports of the AWG.

[0073] The 90-degree optical mixer is as shown in Figure 2 . It includes a signal light input waveguide 711, a local oscillator light input waveguide 601, one 1×2 MMI 60, and three 2×2 MMIs (70, 71, 72), a bent waveguide 80 connecting the four MMIs, and four output waveguides (701, 702, 721, 722); the local oscillator light input waveguide is connected to the input terminal 601 of the 1×2 MMI, and the signal light input waveguide is connected to the input terminal 711 of the bottom 2×2 MMI. Through four 90-degree bent waveguides, the signal light and the local oscillator light are input into the multimode interference regions of the two-side 2×2 MMIs 70 and 72, so that the signal light and the local oscillator light are mixed in the two-side 2×2 MMIs (70, 72). The output terminals (721, 722) of the left 2×2 MMI 72 are connected to the I-channel waveguides (103, 106), and the output terminals (701, 702) of the right 2×2 MMI 70 are connected to the Q-channel waveguides (104, 105). Heating electrodes are respectively provided at the four 90-degree bent waveguides. During use, the electrodes are connected to an external power supply to heat the waveguides, and the refractive index of the waveguides is changed by the thermo-optic effect to change the optical path, realizing the phase tunable function.

[0074] The 2×2 MMI is as shown in Figure 3 . The contour structures at both ends of the traditional rectangular multimode interference region are optimized to be parabolic. Taking the center of the 2×2 MMI as the coordinate origin, the boundary function expression in the first quadrant is:

[0075] y = min([W / 2, x0 - (4α / L 2 )x 2 )

[0076] Where W is the width of the 2×2 MMI, L is the length of the 2×2 MMI, x0 is the coefficient of the linear term of the parabola, and α is the coefficient of the quadratic term of the parabola. This new MMI90 with a multimode interference region structure aims to suppress reflections at the relatively sharp input / output interfaces at the edges, thereby reducing unnecessary energy losses, while achieving a good balance between the insertion loss and power imbalance of the MMI. The local oscillator light and the signal light are mixed by the 90-degree optical mixer 10, and two in-phase signals and two quadrature signals are output. The phase information of the signal light can be demodulated according to the optical intensity distribution at the ports. The p-pole 103 of the in-phase signal is input to the AWG20, the n-pole 106 of the in-phase signal is input to the AWG50, the p-pole 104 of the quadrature signal is input to the AWG30, and the n-pole of the quadrature signal is input to the AWG40.

[0077] Figure 4 The figure shows a schematic diagram of the AWG input coupler. The input end 91 is used to receive the output optical signal of the 90-degree optical mixer 10. Optical signals of different wavelengths are diffracted in the FPR of the input coupler 92. Since the ports 93 of the arrayed waveguides are located on the circumference of the grating circle, the diffracted light of different wavelengths will reach the input ends 93 of each arrayed waveguide with the same phase. After the diffracted light is coupled into the arrayed waveguides 94, it propagates independently. Also, due to the constant length difference between adjacent arrayed waveguides, for light of a certain wavelength, there is a constant phase difference after being output from adjacent arrayed waveguides, forming a multi-beam interference pattern at the output end of the output coupler 96. For light of different wavelengths, because the phase differences are different, the positions of the maxima of the interference patterns are also different. By placing the output waveguides 97 at these positions, light of different wavelengths can be output from different waveguides. Finally, the optical signals in the output waveguides 97 are coupled into the fiber array for further detection.

[0078] Figure 5 It shows the phase error of the silicon-based star-shaped 90-degree optical mixer of this embodiment, and the phase error is less than 1 degree within the C band. Figure 6 It shows a schematic diagram of the channel characteristics of the silicon-based AWG of this embodiment. The loss of the AWG is less than 3 dB, the crosstalk is better than -16 dB, the output channel frequency interval is 200 GHz, and the 3 dB bandwidth is about 150 GHz.

[0079] Using the wavelength division multiplexing 90-degree optical mixing chip described in claim 1, a signal modulation transmission and demodulation system is designed, and the effects of modulating and demodulating QPKS signals and QAM signals in this system are simulated and verified. The signal baud rate of the system is set to 50 Gbaud. The QPSK signal and the QAM signal are respectively loaded onto optical carriers with wavelengths of 1543.6 nm, 1545.2 nm, 1546.8 nm, 1550 nm, 1551.6 nm, 1553.2 nm, 1554.8 nm, 1556.4 nm and a line width of 0.1 MHz. The channel wavelengths of the AWG described in claim 1 are adjusted by a thermal electrode to match the optical carrier wavelengths. After multiplexing, the signals are transmitted in a single-mode optical fiber.

[0080] Figure 7 (a)7(b) and Figure 8 (a)8(b) respectively show the spectrograms of the QPSK signal and the QAM signal after IQ conversion and multiplexing. Among them, each symbol of the QPSK signal represents 2 bits of data, and each symbol of the QAM signal represents 4 bits of data. The input signal is demodulated and wavelength-division multiplexed by the wavelength division multiplexing 90-degree optical mixing chip described in claim 1, and then the optical signal is converted into an electrical signal by a photodetector and a differential amplifier circuit, and further processed by an ADC and a DSP. When the central wavelength is 1550 nm, the constellation diagrams and eye diagrams of the demodulated QPSK signal and QAM signal are respectively as Figure 9 (a)(b) and Figure 10 (a)(b) shown. Due to the phase error of the 90-degree optical mixer, the signal points in the constellation diagram will have slight changes, manifested as offsets in the horizontal and vertical directions; due to the Gaussian channel filtering of the AWG, the signal will have slight distortion, and the ideal circle becomes a water droplet shape. The bit error rate (BER) of 8 channels obtained by simulation is close to 0, indicating that the wavelength division multiplexing 90-degree optical mixing chip of this embodiment can achieve coherent demodulation efficiently and accurately.

[0081] As described above, the wavelength division multiplexing 90-degree optical mixing chip of the present invention has the following beneficial effects:

[0082] The present invention provides a wavelength division multiplexing 90-degree optical mixing chip with low crosstalk, large channel bandwidth and low phase deviation. The present invention uses a multimode interference coupler to achieve the 90-degree optical mixing function, and uses an AWG to achieve the wavelength division multiplexing and demultiplexing functions, providing a solution for realizing low-power and high-rate data transmission, and having high industrial utilization value.

[0083] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

[0084] It should be noted that the above embodiments are not used to limit the protection scope of the present invention, and equivalent transformations or substitutions made on the basis of the above technical solutions all fall within the protection scope of the claims of the present invention.

Claims

1. A multi-channel wavelength division multiplexing 90-degree optical mixing chip, characterized in that: The chip is composed of a signal light input waveguide, a local oscillator light input waveguide, a 90-degree optical mixer, four AWGs and an output waveguide, wherein the 90-degree optical mixer and the four AWGs are provided with heating electrodes, the signal light and the local oscillator light are coherently mixed in the 90-degree optical mixer to form a group of in-phase signals and a group of orthogonal signals, wherein the two in-phase signal output ends of the 90-degree optical mixer are respectively connected to the input ends of AWG1 and AWG4, and the two orthogonal signal output ends are respectively connected to the input ends of AWG2 and AWG3, and the AWG output optical signals are coupled to the optical fiber array; The 90-degree optical mixer includes one 1×2MMI and three 2×2MMIs, four curved waveguides and four output waveguides; the local oscillator light input waveguide is connected to the 1×2MMI input end, the signal light input waveguide is connected to the bottom 2×2MMI input end, and the signal light and the local oscillator light are input to the 2×2MMI multimode interference areas on both sides through the four 90-degree curved waveguides, so that the signal light and the local oscillator light are mixed in the 2×2MMI on both sides, and are respectively led out to the I-channel output waveguide and the Q-channel output waveguide. Heating electrodes are respectively provided at the four 90-degree curved waveguides, and phase tuning is performed by using the thermo-optical effect to reduce the phase imbalance between the I-channel and the Q-channel; The 2×2 MMI includes two input tapers, a multimode interference region with parabolic boundary optimization, and two output tapers, where the multimode interference region is 6.5 microns in length and 2.4 microns in width; The four-way curved waveguide is used to connect four MMIs, and each curved waveguide is composed of two nonlinear curved tapers, which uniformly transition from 0.5 micron width to 2 micron width, and then uniformly transition to 0.5 micron width.

2. The multi-channel wavelength division multiplexing 90-degree optical mixing chip according to claim 1, characterized in that: The AWG comprises an input channel waveguide, an input coupler, an array waveguide, an output coupler and an output channel waveguide, and the array waveguide area is covered with a heating electrode.

3. The multi-channel wavelength division multiplexing 90-degree optical mixing chip according to claim 2, characterized in that: The input coupler includes an input channel taper, a free transmission flat plate region FPR and 43 arrayed waveguide tapers, wherein the FPR is composed of a Rowland circle and a part of a grating circle, the radius of the grating circle is 222.46 microns, the radius of the Rowland circle is half of the radius of the grating circle, the input channel taper is located on one side of the Rowland circle, and the 43 arrayed waveguide tapers are evenly spaced on the circumference of the grating circle, and their extended lines intersect at the central input channel, i.e., the center of the grating circle; the 43 arrayed waveguide tapers are connected to the arrayed waveguide, and the arrayed waveguide is designed to be a multimode waveguide with a width of 2 microns.

4. The multi-channel wavelength division multiplexing 90-degree optical mixing chip according to claim 3, characterized in that: The output coupler includes 43 arrayed waveguide tapers, a free transmission flat plate region FPR and 8 output channel tapers, wherein the FPR is composed of a Rowland circle and a part of a grating circle, the radius of the Rowland circle is half of the radius of the grating circle, the 43 arrayed waveguide tapers are evenly spaced and distributed on one side of the grating circle, and their extended lines intersect at the central output channel, i.e., the center of the grating circle, the 43 arrayed waveguide tapers are connected to the arrayed waveguide, and the arrayed waveguide is designed to be a multimode waveguide with a width of 2 microns.

5. The multi-channel wavelength division multiplexing 90-degree optical mixing chip according to claim 4, characterized in that The heating electrode is composed of two electrodes with a common cathode in a "snake-like arrangement" connected in parallel, which reduces the voltage required for heating while ensuring the heating effect.

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