Polarization controller and optical chip

Abstract

The application relates to the field of photonic integrated circuits, in particular to a polarization controller and an optical chip, and aims to solve the technical problem of how to improve the design of the polarization controller and improve the output power. For this purpose, the polarization controller comprises a plurality of polarization rotation beam splitters arranged in parallel, a phase shifter corresponding to each polarization rotation beam splitter, and all the phase shifters are synchronously phase-shifted controlled by a common control electrode. By arranging a plurality of polarization rotation beam splitters in parallel, the energy of the input optical signal can be maximized to improve the input coupling efficiency; by uniformly regulating all the phase shifters, the accuracy and stability of phase regulation are greatly improved, the wavefront consistency of the multiple optical signals can be ensured, the combiner can realize the maximum coupling efficiency of all the optical signals, and thus the optical signal with the maximum output power is obtained.

Description

Technical Field

[0001] This application relates to the field of photonic integrated circuits, specifically to a polarization controller and an optical chip. Background Technology

[0002] The silicon-based polarization rotating beam splitter (PRS) is a core device based on silicon photonics integration technology. It achieves precise control and efficient beam splitting of the polarization state of optical signals through waveguide structures and has been widely used in optical communication, quantum information processing and other fields.

[0003] Traditional polarization rotating beam splitters can effectively separate TE and TM polarization modes and convert TM mode to TE mode. However, after beam splitting, an uncontrollable relative phase difference exists between the TE light from the original source and the converted TE light, which is difficult to detect. This directly affects the output power of the optical signal obtained after combining the two TE beams. Therefore, improving the polarization controller design to increase output power has become an urgent problem to be solved. Utility Model Content

[0004] In order to overcome the above-mentioned defects, this application is made to solve the technical problem of how to improve the design of polarization controller and increase output power.

[0005] In a first aspect, a polarization controller is provided, comprising: A polarization rotating beam splitter array, comprising N polarization rotating beam splitters, where N is an integer greater than or equal to 2; The phase shifter array includes N phase shifters, each of which corresponds to one of the N polarization rotation beam splitters. Each phase shifting electrode of the N phase shifters is connected to a common control electrode to achieve synchronous control of the N phase shifters. A beam combiner, the input of which is connected to the output of a polarization rotating beam splitter array; A directional coupler, the input of which is connected to the output of the combiner.

[0006] In one technical solution of the aforementioned polarization controller, the N polarization rotating beam splitters have the same structure and are arranged in parallel to achieve synchronous acquisition of input optical signals at the N input ends of the polarization rotating beam splitters.

[0007] In one technical solution of the aforementioned polarization controller, the polarization rotation beam splitter includes a first output terminal and a second output terminal, wherein: N phase shifters correspond to N first output terminals respectively; or... N phase shifters correspond to N second output terminals respectively.

[0008] In one technical solution of the aforementioned polarization controller, The optical signal transmission length between each first output terminal and its corresponding input terminal in the combiner is the same; The optical signal transmission length between each second output terminal and its corresponding input terminal in the combiner is the same.

[0009] In one technical solution of the aforementioned polarization controller, the directional coupler is a non-uniform power splitting ratio directional coupler, including: First power output terminal and second power output terminal; The output power of the first power output terminal is greater than the output power of the second power output terminal.

[0010] In one technical solution of the above-mentioned polarization controller, the polarization controller further includes: Interlayer coupler, the input waveguide of the interlayer coupler is connected to the second power output terminal, the output waveguide of the interlayer coupler is set in a different device layer than the input waveguide, and the orthogonal projections of the output waveguide and the input waveguide on the substrate overlap.

[0011] In one of the above-mentioned polarization controller technical solutions, both the input waveguide and the output waveguide are tapered waveguides.

[0012] In one technical solution of the aforementioned polarization controller, The output waveguide is disposed in the first device layer, which is based on silicon. A polarization rotating beam splitter array, a beam combiner, a directional coupler, and an input waveguide are disposed in a second device layer, which is based on silicon nitride.

[0013] In one technical solution of the above-mentioned polarization controller, the polarization controller further includes: A photodetector is used to convert the received optical signal from the second power output terminal into an electrical signal, wherein the electrical signal can be used as a feedback signal for the control of the phase shifter array.

[0014] In a second aspect, an optical chip is provided, the optical chip including a polarization controller according to any of the above technical solutions.

[0015] The above-mentioned technical solutions of this application have at least one or more of the following beneficial effects: By using multiple polarization rotating beams with identical structures and arranged in parallel, input optical signals including TE / TM modes from the input optical fiber can be captured simultaneously, reducing the optical loss caused by alignment errors or mode field mismatch of a single polarization rotating beam splitter, thereby maximizing the capture of the energy of the input optical signal and improving the input coupling efficiency; by uniformly controlling the phase shifter array, the optical signals passing through each phase shifter can produce the same phase change, ensuring the wavefront consistency of multiple optical signals, so that each optical signal in the input beam combiner has the best phase difference, achieving the maximum coupling efficiency of all optical signals, thereby obtaining the optical signal with the maximum output power. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a polarization controller according to one embodiment of this application.

[0017] Figure 2 This is a cross-sectional structural diagram of the phase shifter array region in a polarization controller according to one embodiment of this application.

[0018] Figure 3 This is a schematic diagram of a polarization controller according to another embodiment of this application.

[0019] Figure 4 yes Figure 3 A schematic diagram of the cross-sectional structure of the interlayer coupler along the BB' direction. Detailed Implementation

[0020] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0021] It should be noted that in the description of this application, the terms "upper," "lower," "left," "right," "inner," and "outer," which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device, structure, or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] Figure 1 This is a schematic diagram of a polarization controller according to one embodiment of this application. Figure 1As shown, the polarization controller of this application includes: a polarization rotating beam splitter array 100, a phase shifter array 200, a beam combiner 300, a directional coupler 400, and a photodetector 500, wherein the polarization rotating beam splitter array 100, the beam combiner 300, the directional coupler 400, and the photodetector 500 are disposed in a first device layer, and the material of the first device layer is silicon.

[0023] The polarization rotating beam splitter array 100 includes a first polarization rotating beam splitter 110, a second polarization rotating beam splitter 120, and a third polarization rotating beam splitter 130.

[0024] The three polarization rotating beamsplitters (110, 120, and 130) in the polarization rotating beamsplitter array 100 have identical structures and are arranged in parallel. Therefore, when a TE / TM mode optical signal enters the polarization rotating beamsplitter array 100 from the input fiber through end-face coupling, each input end of the three polarization rotating beams can synchronously acquire input optical signals including TE and TM modes, thereby reducing optical loss caused by alignment errors or mode mismatch in a single polarization rotating beamsplitter.

[0025] When a polarization controller uses multiple polarization rotating beamsplitters to synchronously acquire input optical signals in TE / TM mode, the output of the polarization rotating beamsplitter array will include TE light (original TE light) from multiple input optical signals and multiple TE light after mode conversion (converted TE light). How to effectively control the phase difference between multiple original TE light beams and multiple converted TE light beams to obtain the maximum combined output power is also a technical problem that needs to be solved in the design of polarization controllers. Accordingly, this application proposes a technical solution for synchronously adjusting the phase difference between multiple original TE light beams or multiple converted TE light beams.

[0026] Continue reading Figure 1 When the TE / TM mode optical signal enters the polarization rotating beam splitter, the TE mode optical signal (TE light) cannot couple to the cross waveguide due to phase mismatch. Therefore, it maintains its original mode and is output from the first output terminal (TE1) along the straight waveguide (111, 121 and 131). The TM mode optical signal (TM light) satisfies the phase matching condition, is coupled to the cross waveguide (112, 122 and 132), and is converted into TE light and output from the second output terminal (TE2).

[0027] Since the three polarization rotating beam splitters (110, 120 and 130) have the same structure, the three TE beams output from the first output terminal (TE1) have the same phase; the three TE beams output from the second output terminal (TE2) have the same phase.

[0028] The phase shifter array 200 includes a first phase shifter 210, a second phase shifter 220, and a third phase shifter 230. The three phase shifters in the phase shifter array 200 correspond to the three first output terminals of the three polarization rotating beamsplitters in the polarization rotating beamsplitter array 100, respectively.

[0029] Specifically, the first phase shifter 210 is positioned directly above the connecting waveguide 610 between the first output of the first polarization rotating beam splitter 110 and one input of the beam combiner 300.

[0030] The second phase shifter 220 is positioned directly above the connecting waveguide 630 between the first output of the second polarization rotating beam splitter 120 and one input of the beam combiner 300.

[0031] The third phase shifter 230 is positioned directly above the connecting waveguide 650 between the first output of the third polarization rotating beam splitter 130 and one input of the beam combiner 300.

[0032] The three second outputs of the three polarization rotating beamsplitters in the polarization rotating beamsplitter array 100 are connected to the other three inputs of the beam combiner 300 through waveguides 620, 640 and 660, respectively.

[0033] Waveguides 610, 630, and 650 have the same length, meaning that the optical signal transmission length between each first output terminal of the polarization rotating beamsplitter array 100 and its corresponding input terminal of the beam combiner 300 is the same. Waveguides 620, 640, and 660 have the same length, meaning that the optical signal transmission length between each second output terminal of the polarization rotating beamsplitter array 100 and its corresponding input terminal of the beam combiner 300 is the same.

[0034] In other words, when the TE light output from each of the first output terminals of the polarization rotating beam splitter array 100 reaches the corresponding input terminal of the beam combiner 300, the phases of each TE light are the same. When the TE light output from each of the second output terminals of the polarization rotating beam splitter array 100 reaches the corresponding input terminal of the beam combiner 300, the phases of each TE light are the same.

[0035] In another embodiment, the three phase shifters in the phase shifter array 200 can also correspond to the three second outputs of the three polarization rotating beamsplitters in the polarization rotating beamsplitter array 100, that is, the three phase shifters (210, 220 and 230) are respectively positioned directly above the three connecting waveguides (620, 640 and 660) between the three second outputs and the three inputs of the beam combiner 300.

[0036] In this application, the beam combiner 300 has 6 input terminals. At this time, there is a one-to-one correspondence between the 6 output terminals of the polarization rotation beam splitter array 100 and the 6 input terminals of the beam combiner 300. As an example, the beam combiner 300 is a 6*1 MMI (Multimode Interference) beam combiner (i.e., a multimode interference beam combiner).

[0037] As can be seen from the above, when the polarization rotating beam splitter array 100 includes N polarization rotating beam splitters (each polarization rotating beam splitter includes two output terminals), the polarization rotating beam splitter array 100 has a total of 2N output terminals. Correspondingly, the beam combiner 300 includes 2N input terminals that correspond one-to-one with the 2N output terminals.

[0038] Continue reading Figure 2 , Figure 2 This is a cross-sectional structural diagram of the phase shifter array region in a polarization controller according to one embodiment of this application, including a silicon substrate 10, a buried oxide layer 20, a first device layer (610, 620, 630, 640, 650, and 660) obtained by patterning, a first dielectric layer 30, and a second dielectric layer 40. The first device layer is made of silicon, and the buried oxide layer 20, the first dielectric layer 30, and the second dielectric layer 40 are all made of silicon dioxide. Further, the first device layer is made of single-crystal silicon.

[0039] The first phase shifter 210 is located directly above the waveguide 610. The first phase shifter 210 includes a phase shifting electrode 211, a tungsten column 212 and a corresponding control electrode. The phase shifting electrode 211 is electrically connected to the common control electrode 50 above the second dielectric layer 40 through the tungsten column 212.

[0040] The second phase shifter 220 is located directly above the waveguide 630. The second phase shifter 220 includes a phase shifting electrode 221, a tungsten column 222, and a corresponding control electrode. The phase shifting electrode 221 is electrically connected to the common control electrode 50 above the second dielectric layer 40 through the tungsten column 222.

[0041] The third phase shifter 230 is located directly above the waveguide 650. The third phase shifter 230 includes a phase shifting electrode 231, a tungsten pillar 232, and a corresponding control electrode. The phase shifting electrode 231 is electrically connected to the common control electrode 50 above the second dielectric layer 40 through the tungsten pillar 232.

[0042] In other words, the control electrodes of each phase shifter in the phase shifter array 200 are connected in parallel to form a common control electrode 50, so that the same control signal can be applied to each phase shifter to achieve synchronous phase shifting control of each phase shifter.

[0043] It should be noted that this application does not limit the specific structure of the common control electrode. As an example, the first control terminals (e.g., positive power supply) of each phase shifter control electrode are connected in parallel via metal wires to form the first common control electrode 50; the second control terminals (e.g., negative power supply) of each phase shifter control electrode are connected in parallel via metal wires to form the second common control electrode 50. Those skilled in the art can design the specific structure of the common control electrode according to actual conditions, as long as the phase shifting electrodes of each phase shifter can apply the same control signal.

[0044] By uniformly controlling the phase shifter array 200 through the common control electrode 50, the several optical signals passing through each phase shifter can produce the same phase change. This means that the multiple optical signals input to the combiner 300 can achieve the same phase (i.e., zero phase difference), resulting in the highest coupling efficiency. Therefore, this "coordinated control" ensures wavefront consistency, greatly improves the accuracy and stability of phase control, and to a certain extent avoids the errors caused by separate control.

[0045] In the embodiments of this application, the phase shifter is an electro-optic modulator, and the phase shift electrodes 211, 221, and 231 can be made of metallic materials such as aluminum-copper alloys. When the common control electrode 50 applies an electrical control signal, the electric field of the phase shift electrodes (211, 221, and 231) changes, altering the effective refractive index of the waveguides (610, 630, and 650) below them, thereby changing the optical path of the light wave and achieving phase shift control.

[0046] It should be noted that this application does not limit the specific structure or materials of the phase shifter, as long as it can achieve the phase shifting function. As an example, the phase shifter can also be a thermo-optic modulator, which uses heat to change the effective refractive index of the waveguide to achieve phase shift control. In this case, the modulation electrode of the thermo-optic modulator can be made of titanium / titanium nitride (Ti / TiN) material. Without departing from the principles of this application, those skilled in the art can make equivalent modifications or substitutions to the relevant technical features, and all such modifications or substitutions will fall within the protection scope of this application.

[0047] Three phase-modulated TE beams and three unmodulated TE beams converted from TM beams enter the combiner 300 and are combined into a single TE beam, which is then output from the output end of the combiner 300.

[0048] The output of the beam combiner 300 is connected to the input of the directional coupler 400. The directional coupler 400 is a non-uniform power splitting ratio directional coupler, and the splitting power ratio of the two optical signals output by the directional coupler 400 can be set to 9:1. At this time, the high-power TE light is output from the first power output terminal output1, and the low-power TE light is output from the second power output terminal output2.

[0049] In other embodiments, the beam splitting power ratio of the directional coupler 400 can also be changed by adjusting the size of the coupling gap and / or the coupling length between the two parallel waveguides in the directional coupler 400, for example, by setting the beam splitting power ratio of the directional coupler 400 to 99:1 or other values.

[0050] The second power output terminal of the directional coupler 400 is connected to the photodetector 500. The photodetector 500 receives the TE light output from the second power output terminal and converts the TE light into an electrical signal, which serves as the feedback signal for phase modulation of the phase shifter array 200. As an example, according to a set step size, a control signal is continuously applied to the phase shifter array 200 through the common control electrode 50, while the value of the electrical signal (feedback signal) output by the photodetector 500 is recorded. The control signal value corresponding to the maximum value of the feedback signal (e.g., the maximum value of the photodetector output voltage) is selected as the optimal control signal for the phase shifter array 200.

[0051] Through the closed-loop feedback control based on the polarization controller of this application, the TE beams at each input end of the input combiner 300 can be made to have the same phase, that is, the phase difference between the TE beams at each input end of the input combiner 300 is about zero, thereby achieving the maximum coupling efficiency of all optical signals, enabling the first power output end to output the maximum optical power, and thus supporting high-efficiency TE light conversion output for dual polarization modes with arbitrary ratio input of TE / TM light.

[0052] In another embodiment, the polarization rotating beam splitter array 100, beam combiner 300, and directional coupler 400 can also be fabricated using silicon nitride, i.e., the waveguide portion is disposed in a silicon nitride device layer (e.g., Figure 4 (The second device layer in the middle).

[0053] Since photodetectors 500 are typically fabricated using silicon, they are usually placed in other device layers (e.g., silicon nitride device layers) outside of the silicon nitride device layer. Figure 4 (The first device layer in the process). At this point, interlayer coupling is necessary to couple the optical signal from the silicon nitride device layer (the second device layer) to the first device layer where the photodetector 500 is located.

[0054] like Figure 3 As shown, an interlayer coupler 700 is also included between the second power output terminal of the coupler 400 and the photodetector 500. The optical signal (output by output2) in the silicon nitride device layer can be transmitted to the photodetector 500 in the first device layer through the interlayer coupler 700.

[0055] The input waveguide 710 of the interlayer coupler 700 is disposed in the second device layer and connected to the second power output terminal of the coupler 400; the output waveguide 720 of the interlayer coupler 700 is disposed in the first device layer and connected to the input terminal of the photodetector 500.

[0056] The input waveguide 710 and output waveguide 720 of the interlayer coupler 700 are both tapered waveguides. The side of the input waveguide 710 near the second power output terminal of the coupler 400 is the wide end of the tapered waveguide; the side of the output waveguide 720 near the photodetector 500 is the wide end of the tapered waveguide. The narrow ends of the two tapered waveguides are arranged opposite each other, and the narrow end of each tapered waveguide overlaps with the orthographic projection of the other tapered waveguide on the substrate. The orthographic projection of the centerlines of the two waveguides on the substrate coincides as a straight line.

[0057] Continue reading Figure 4 , Figure 4 yes Figure 3 A cross-sectional view of the interlayer coupler 700 along the BB' direction shows that it includes a silicon substrate 10, a buried oxide layer 20, an output waveguide 720 of the first device layer, a first dielectric layer 30, an input waveguide 710 of the second device layer, and a second dielectric layer 40, wherein the buried oxide layer 20, the first dielectric layer 30, and the second dielectric layer 40 are all made of silicon dioxide.

[0058] In this tapered waveguide coupling structure (varying from wide to narrow or from narrow to wide), light waves couple from the silicon nitride waveguide to the silicon waveguide via evanescent waves with almost no energy loss. Furthermore, since the refractive index of silicon nitride (approximately 2.0) is between that of silicon (approximately 3.5) and silicon dioxide (approximately 1.45), when the second device layer waveguide is made of silicon nitride, this moderate refractive index reduces the mode mismatch between the input fiber (refractive index approximately 1.45) and the silicon nitride waveguide (polarization rotating beam splitter array 100), thereby reducing Fresnel reflections and mode field mismatch losses at the end face. Additionally, the silicon nitride waveguide exhibits lower propagation loss and a wider transparency window in the visible to near-infrared bands, further improving coupling efficiency. Simultaneously, silicon nitride has low polarization sensitivity, reducing polarization-dependent losses.

[0059] It should be noted that in this embodiment, the polarization rotating beamsplitter array 100 contains three polarization rotating beamsplitters, but this is not a limitation. The main purpose of using multiple parallel polarization rotating beamsplitters is to maximize the capture of the energy of the input optical signal (improving input coupling efficiency), thereby increasing the output power of the polarization controller and achieving efficient polarization rotating beam splitting. Accordingly, depending on the actual situation, the polarization rotating beamsplitter array 100 can contain fewer or more polarization rotating beams, such as two, four, six, etc. Considering factors such as system size (volume), manufacturing cost, process complexity, optical loss (efficiency), and long-term reliability, three to six beams are generally considered optimal.

[0060] Furthermore, the aforementioned polarization controller can be implemented using semiconductor processes. To this end, this application also provides an optical chip that can be fabricated based on an SOI silicon wafer or a silicon substrate.

[0061] Taking SOI silicon wafers as an example, such as Figure 2 As shown, the optical chip includes a silicon substrate 10, a buried oxide layer 20, and a first device layer, wherein the buried oxide layer serves as the cladding of the waveguide. Figure 1 The polarization rotating beam splitter array 100, beam combiner 300, directional coupler 400, photodetector 500, and waveguides (610, 620, 630, etc.) are formed in a patterned form in the first device layer.

[0062] A first dielectric layer 30 is covered above the first device layer. The first dielectric layer 30 serves as the cladding of the waveguide, filling the gaps between the aforementioned components and covering each component. A patterned phase-shifting electrode (211, 221, and 231) is formed above the first dielectric layer. A second dielectric layer 40 is also covered above the phase-shifting electrode, filling the gaps between each phase-shifting electrode and covering each phase-shifting electrode. A patterned common control electrode 50 is formed above the second dielectric layer 40. Interlayer electrical connection structures (212, 222, and 232) are used to electrically connect the common control electrode 50 to each phase-shifting electrode (211, 221, and 231).

[0063] As an example, the buried oxide layer 20, the first dielectric layer 30 and the second dielectric layer 40 are all made of silicon dioxide, the phase-shifting electrodes (211, 221 and 231) are made of aluminum-copper alloy, the interlayer electrical connection structure (212, 222 and 232) is made of tungsten metal, and the common control electrode 50 is made of copper metal or aluminum-copper alloy.

[0064] It should be noted that the specific structure of the polarization rotating beam splitters (110, 120, and 130) is not limited in this application. As an example, such as... Figure 1The asymmetric Y-shaped structure is shown. Those skilled in the art can design the specific structure of the polarization rotating beam splitter according to actual conditions, as long as it can achieve functions such as separating TM light from TE light and converting TM light into TE light. Similarly, the specific structures of the beam combiner 300, directional coupler 400, and photodetector 500 are not limited in this application, as long as they can achieve the corresponding functions.

[0065] It should be noted that the optical chip described in this application can be an optical chip that only includes the polarization controller described in this application, serving as a light source mode conversion device; or it can be based on the polarization controller described in this application with the addition of other structures. For example, it can include wavelength division multiplexing structures, large-scale optical switch arrays, etc., to form an optical computing chip for use in data centers and other fields; or it can be integrated with high-speed modulators, SOA arrays, etc., to achieve on-chip transceiver integration, forming a high-speed optical communication chip, etc.

[0066] The technical solution of this application has been described above with reference to one embodiment shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A polarization controller, characterized in that, include: A polarization rotating beam splitter array, comprising N polarization rotating beam splitters, where N is an integer greater than or equal to 2; A phase shifter array includes N phase shifters, wherein each of the N phase shifters corresponds one-to-one with the N polarization rotating beam splitters, and each phase shifting electrode of the N phase shifters is connected to a common control electrode to achieve synchronous control of the N phase shifters; A beam combiner, the input of which is connected to the output of the polarization rotating beam splitter array; A directional coupler, wherein the input end of the directional coupler is connected to the output end of the bundle combiner.

2. The polarization controller according to claim 1, characterized in that, The N polarization rotating beam splitters have the same structure and are arranged in parallel to enable the N input ends of the polarization rotating beam splitters to synchronously acquire the input optical signal.

3. The polarization controller according to claim 1, characterized in that, The polarization rotating beam splitter includes a first output terminal and a second output terminal, wherein: The N phase shifters correspond to the N first output terminals respectively; or... The N phase shifters correspond to the N second output terminals respectively.

4. The polarization controller according to claim 3, characterized in that, The optical signal transmission length between each of the first output terminals and its corresponding input terminals in the beam combiner is the same. The optical signal transmission length between each of the second output terminals and its corresponding input terminals in the combiner is the same.

5. The polarization controller according to claim 1, characterized in that, The directional coupler is a non-uniform power splitting ratio directional coupler, comprising: First power output terminal and second power output terminal; The output power of the first power output terminal is greater than the output power of the second power output terminal.

6. The polarization controller according to claim 5, characterized in that, The polarization controller further includes: An interlayer coupler, wherein the input waveguide of the interlayer coupler is connected to the second power output terminal, and the output waveguide of the interlayer coupler is disposed on a different device layer than the input waveguide, and the orthogonal projections of the output waveguide and the input waveguide on the substrate overlap.

7. The polarization controller according to claim 6, characterized in that, Both the input waveguide and the output waveguide are tapered waveguides.

8. The polarization controller according to claim 6, characterized in that, The output waveguide is disposed in a first device layer, which is based on silicon. The polarization rotating beam splitter array, the beam combiner, the directional coupler, and the input waveguide are disposed in a second device layer, which is fabricated based on silicon nitride.

9. The polarization controller according to any one of claims 5 to 8, characterized in that, The polarization controller further includes: A photodetector is used to convert the received optical signal output from the second power output terminal into an electrical signal, wherein the electrical signal can serve as a feedback signal for the control of the phase shifter array.

10. An optical chip, characterized in that, The optical chip includes a polarization controller according to any one of claims 1 to 9.

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