A 4x4 optical waveguide encoder

Abstract

A 4×4 optical waveguide encoder, belonging to the field of photonic integration technology, is disclosed. It consists of a substrate, a lower cladding, a core layer, an upper cladding, and electrodes. The core layer and upper cladding are located on the upper surface of the lower cladding, with the core layer encased within the upper cladding. The core layer comprises 16 switching units, 8 phase shifter units, 12 cross-waveguide units, and 16 beam combiner units. This invention achieves a high-density integrated 4×4 optical waveguide encoder with reconfigurable optical logic gates through a driving method using thermo-optical switches as units, in conjunction with phase shifting, cross-waveguide, and beam combining units. This technology is suitable for constructing programmable photonic integrated networks and has broad application prospects in big data centers and ultrafast computing systems. Compared to traditional encoders, this invention employs a scheme of multiple cascaded metal thermoelectrodes, which greatly simplifies the circuit control scheme; the scheme of controlling the coupling state by heating with metal thermoelectrodes reduces the size of the unit structure and improves the integration density.

Description

Technical Field

[0001] This invention belongs to the field of photonic integration technology, specifically relating to a 4×4 optical waveguide encoder. Background Technology

[0002] With the rapid development of optical communication technology, optical switching networks, due to their advantages of large information capacity and strong anti-interference capability, are gradually replacing electrical switching networks as the mainstream development direction of modern communication. Free-space optical devices and planar optical devices are two important components of optical switching networks. The high signal response speed of planar optical switching networks is more suitable for fabricating highly compatible and efficient multifunctional photonic chips. In particular, on-chip optical waveguide coding devices based on optical code division multiple access (OCDMA) technology have attracted much attention in optical computing systems due to their high integration, low power consumption, and fast response speed. However, the cascading of multiple components limits the scalability of the overall encoder and the reconfigurability of the logic gates. Summary of the Invention

[0003] The purpose of this invention is to improve the scalability and reconfigurability of encoders and logic gates. A 4×4 optical waveguide encoder is proposed, which utilizes thermo-optical modulation of the effective refractive index of the optical waveguide and optical waveguide coupling technology to provide an optical waveguide encoder suitable for building high-speed, highly integrated optical coding systems. This invention achieves a high-density integrated 4×4 optical waveguide encoder with reconfigurable optical logic gates through a driving method using thermo-optical switches as units, in conjunction with phase-shifting, cross-connecting, and beam-combining units. This technology is applicable to the construction of programmable photonic integrated networks and has broad application prospects in big data centers and ultrafast computing systems.

[0004] The 4×4 optical waveguide encoder of this invention adopts the following technical solution:

[0005] like Figure 1 As shown in (a), the 4×4 optical waveguide encoder of the present invention consists of a substrate layer 1, a lower cladding layer 2, a core layer 3, an upper cladding layer 4, and an electrode 5 from bottom to top. Figure 1 (a) Section at β is as follows Figure 1 As shown in (b), the core layer 3 has a rectangular structure on the cross section perpendicular to the light transmission direction. The core layer 3 and the upper cladding layer 4 are located on the upper surface of the lower cladding layer 2, and the core layer 3 is encased in the upper cladding layer 4. The electrode 5 is located on the surface of the upper cladding layer 4 and consists of a narrow rectangular metal thermoelectrode, a wide rectangular metal connecting line, and a square external power supply connecting lead. The square external power supply connecting lead is connected to an external regulated power supply to provide modulation voltage for the 4×4 optical waveguide encoder. The current output by the square external power supply connecting lead is transmitted to the narrow rectangular metal thermoelectrode through the wide rectangular metal connecting line. The narrow rectangular metal thermoelectrode has a high resistance and generates high heat after pressure is applied, thereby changing the refractive index of the core layer 3 below the narrow rectangular metal thermoelectrode and achieving the modulation effect.

[0006] The core layer 3 structure of the 4×4 optical waveguide encoder described in this invention is as follows: Figure 1 As shown in Figure c, according to the layout scheme of core layer 3, the optical waveguide encoder can be divided into 16 switching units (A11-A14, A21-A24, A31-A34, A41-A44), 8 phase shifter units (B11, B12, B21, B22, B31, B32, B41, B42), and 12 cross waveguide units (C11-C13, ...). It consists of C21-C23, C31-C33, C41-C43) and 16 bundle combiner units (D11-D14, D21-D24, D31-D34, D41-D44); respectively labeled as the first switch unit (A11), the second switch unit (A12), the third switch unit (A13), the fourth switch unit (A14), the fifth switch unit (A21), the sixth switch unit (A22), the seventh switch unit (A23), the eighth switch unit (A24), the ninth switch unit (A31), and the tenth switch unit (A44). 32) Eleventh switch unit (A33), twelfth switch unit (A34), thirteenth switch unit (A41), fourteenth switch unit (A42), fifteenth switch unit (A43), sixteenth switch unit (A44); first phase shifter unit (B11), second phase shifter unit (B12), third phase shifter unit (B21), fourth phase shifter unit (B22), fifth phase shifter unit (B31), sixth phase shifter unit (B32), seventh phase shifter unit (B41), eighth phase shifter unit (B42); first crossover Waveguide unit (C11), second cross waveguide unit (C12), third cross waveguide unit (C13), fourth cross waveguide unit (C21), fifth cross waveguide unit (C22), sixth cross waveguide unit (C23), seventh cross waveguide unit (C31), eighth cross waveguide unit (C32), ninth cross waveguide unit (C33), tenth cross waveguide unit (C41), eleventh cross waveguide unit (C42), twelfth cross waveguide unit (C43); first beam combiner unit (D11), second beam combiner unit (D12) The following are the bundle combiner units: the third bundle combiner unit (D13), the fourth bundle combiner unit (D14), the fifth bundle combiner unit (D21), the sixth bundle combiner unit (D22), the seventh bundle combiner unit (D23), the eighth bundle combiner unit (D24), the ninth bundle combiner unit (D31), the tenth bundle combiner unit (D32), the eleventh bundle combiner unit (D33), the twelfth bundle combiner unit (D34), the thirteenth bundle combiner unit (D41), the fourteenth bundle combiner unit (D42), the fifteenth bundle combiner unit (D43), and the sixteenth bundle combiner unit (D44).

[0007] The first switching unit (A11), the second switching unit (A12), the third switching unit (A13), the fourth switching unit (A14), the first phase shifter unit (B11), the second phase shifter unit (B12), the first cross waveguide unit (C11), the second cross waveguide unit (C12), the third cross waveguide unit (C13), the first combiner unit (D11), the second combiner unit (D12), the third combiner unit (D13), and the fourth combiner unit (D14) constitute the first 4×4 optical waveguide encoder; the fifth switching unit (A21) The sixth switch unit (A22), the seventh switch unit (A23), the eighth switch unit (A24), the third phase shifter unit (B21), the fourth phase shifter unit (B22), the fourth cross waveguide unit (C21), the fifth cross waveguide unit (C22), the sixth cross waveguide unit (C23), the fifth combiner unit (D21), the sixth combiner unit (D22), the seventh combiner unit (D23), and the eighth combiner unit (D24) constitute the second 4×4 optical waveguide encoder; the ninth switch unit (A31) and the tenth switch unit (A32) The eleventh switch unit (A33), the twelfth switch unit (A34), the fifth phase shifter unit (B31), the sixth phase shifter unit (B32), the seventh cross waveguide unit (C31), the eighth cross waveguide unit (C32), the ninth cross waveguide unit (C33), the ninth combiner unit (D31), the tenth combiner unit (D32), the eleventh combiner unit (D33), and the twelfth combiner unit (D34) constitute the third 4×4 optical waveguide encoder; the thirteenth switch unit (A41), the fourteenth switch unit (A42), and the fifteenth switch unit (A34) constitute the third 4×4 optical waveguide encoder. The first 4×44 optical waveguide encoder is composed of the following units: the switch unit (A43), the sixteenth switch unit (A44), the seventh phase shifter unit (B41), the eighth phase shifter unit (B42), the tenth cross waveguide unit (C41), the eleventh cross waveguide unit (C42), the twelfth cross waveguide unit (C43), the thirteenth combiner unit (D41), the fourteenth combiner unit (D42), the fifteenth combiner unit (D43), and the sixteenth combiner unit (D44). The first to fourth 4×4 optical waveguide encoders are connected in sequence to form a 4×4 optical waveguide encoder.

[0008] The first switch unit (A11), second switch unit (A12), third switch unit (A13), fourth switch unit (A14), fifth switch unit (A21), sixth switch unit (A22), seventh switch unit (A23), eighth switch unit (A24), ninth switch unit (A31), tenth switch unit (A32), eleventh switch unit (A33), twelfth switch unit (A34), thirteenth switch unit (A41), fourteenth switch unit (A42), fifteenth switch unit (A43), and sixteenth switch unit (A44) of the present invention have the following characteristics: Figure 1 The same structure shown in d consists of three parts along the optical transmission direction: a 3-dB coupler (AA), a modulation region (AB), and a directional coupling region (AC). The modulation region (AB) consists of two parallel straight waveguides, with the straight waveguide on the right side of the optical transmission direction serving as the modulation arm. An electrode 5 is disposed on the upper surface of the upper cladding 4 corresponding to its position. The 3-dB coupler (AA) consists of an input single straight waveguide and an output double straight waveguide with a curved coupling waveguide at the end. The input single straight waveguide and the output double straight waveguide are parallel to each other, and the output double straight waveguides are of the same size and symmetrically arranged on the input single straight waveguide. On both sides, the ends of the output double straight waveguides are extended to both sides through curved coupling waveguides and connected to the two parallel straight waveguides of the modulation region (AB) respectively; the directional coupling region (AC) is composed of double straight waveguides with curved coupling waveguides at both ends. The double straight waveguides are the same size and parallel to each other. Their ends are extended to both sides through curved coupling waveguides and connected to the two parallel straight waveguides of the modulation region (AB) respectively. Their ends are extended to both sides through curved coupling waveguides to form the first output end and the second output end; the double straight waveguides of the directional coupling region (AC) have a small spacing, forming a directional coupling structure.

[0009] The first phase shifter unit (B11), second phase shifter unit (B12), third phase shifter unit (B21), fourth phase shifter unit (B22), fifth phase shifter unit (B31), sixth phase shifter unit (B32), seventh phase shifter unit (B41), and eighth phase shifter unit (B42) of the present invention have the following characteristics: Figure 1The same structure shown in e is sequentially composed of an input straight waveguide, two symmetrically arranged trapezoidal waveguides, and an output straight waveguide connected together. The width of the two symmetrically arranged trapezoidal waveguides first widens and then narrows along the optical transmission direction. The first cross waveguide unit (C11), second cross waveguide unit (C12), third cross waveguide unit (C13), fourth cross waveguide unit (C21), fifth cross waveguide unit (C22), sixth cross waveguide unit (C23), seventh cross waveguide unit (C31), eighth cross waveguide unit (C32), ninth cross waveguide unit (C33), tenth cross waveguide unit (C41), eleventh cross waveguide unit (C42), and twelfth cross waveguide unit (C43) of this invention have the following characteristics: Figure 1 The same structure shown in f is formed by two waveguides connected in a cross manner, forming a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first input terminal and the second input terminal are parallel to each other, and the first output terminal and the second output terminal are parallel to each other. The first bundler unit (D11), second bundler unit (D12), third bundler unit (D13), fourth bundler unit (D14), fifth bundler unit (D21), sixth bundler unit (D22), seventh bundler unit (D23), eighth bundler unit (D24), ninth bundler unit (D31), tenth bundler unit (D32), eleventh bundler unit (D33), twelfth bundler unit (D34), thirteenth bundler unit (D41), fourteenth bundler unit (D42), fifteenth bundler unit (D43), and sixteenth bundler unit (D44) of the present invention have the following characteristics: Figure 1 The structure shown in g is a symmetrical multi-surface structure composed of two curved coupled waveguides, a first curved waveguide, a second curved waveguide, a trapezoidal waveguide, and a straight waveguide connected sequentially. The two curved coupled waveguides form the first and second input terminals of the combiner unit, and the straight waveguide forms the output terminal of the combiner unit. The surface width of the combiner unit varies exponentially, first increasing and then decreasing to form the first surface, then increasing and then decreasing again to form the second surface. Finally, the trapezoidal waveguide connects the second curved waveguide and the straight waveguide to control the diffraction order change, which can realize the logic OR gate function. Two signal beams input along the two curved coupled waveguides will be combined into one signal beam and output from the straight waveguide. Alternatively, a single signal beam transmitted along either curved coupled waveguide can be output from the straight waveguide. The 4×4 optical waveguide encoder of this invention has 4 input ports (In1~In4) and 4 output ports (Out1~Out4).

[0010] Specifically, in the first 4×4 optical waveguide encoder, the input straight waveguide of the first phase shifter (B11) is connected to the first output terminal of the directional coupling region (AC) of the first switching unit (A11), and the output straight waveguide of the first phase shifter (B11) is connected to the first input terminal of the first beam combiner (D11); the input straight waveguide of the second phase shifter (B12) is connected to the second output terminal of the directional coupling region (AC) of the fourth switching unit (A14), and the output straight waveguide of the second phase shifter (B12) is connected to the fourth beam combiner (D14). The first input terminal of the first cross waveguide (C11) is connected to the second input terminal of the directional coupling region (AC) of the first switching unit (A11), the second input terminal of the first cross waveguide (C11) is connected to the first output terminal of the directional coupling region (AC) of the second switching unit (A12), the first output terminal of the first cross waveguide (C11) is connected to the second input terminal of the first beam combiner (D11), and the second output terminal of the first cross waveguide (C11) is connected to the first input terminal of the second beam combiner (D12). The input terminals are connected; the first input terminal of the second cross waveguide (C12) is connected to the second output terminal of the directional coupling region (AC) of the second switching unit (A12), the second input terminal of the second cross waveguide (C12) is connected to the first output terminal of the directional coupling region (AC) of the third switching unit (A13), the first output terminal of the second cross waveguide (C12) is connected to the second input terminal of the second beam combiner (D12), and the second output terminal of the second cross waveguide (C12) is connected to the first input terminal of the third beam combiner (D13). The three cross waveguides are connected as follows: the first input terminal of the third cross waveguide (C13) is connected to the second output terminal of the directional coupling region (AC) of the third switching unit (A13); the second input terminal of the third cross waveguide (C13) is connected to the first output terminal of the directional coupling region (AC) of the fourth switching unit (A14); the first output terminal of the third cross waveguide (C13) is connected to the second input terminal of the third beam combiner (D13); and the second output terminal of the third cross waveguide (C13) is connected to the first input terminal of the fourth beam combiner (D14). The signal light after being combined by the first beam combiner unit (D11), the second beam combiner unit (D12), the third beam combiner unit (D13), and the fourth beam combiner unit (D14) is used as the input signal of the second 4×4 optical waveguide encoder, and so on.

[0011] like Figure 1As shown in (h), electrode 5 consists of 16 electrode units (E11-E14, E21-E24, E31-E34, E41-E44). Each electrode unit consists of two square external power supply connection leads, one narrow rectangular metal hot electrode, and two wide rectangular metal connecting lines, which act on the modulation arm of the modulation area (AB) of the switching unit (A11-A14, A21-A24, A31-A34, A41-A44). The square external power supply connection leads are evenly distributed on both sides of the 4×4 optical waveguide encoder. The narrow rectangular metal hot electrodes are arranged on the surface of the cladding 4 at the corresponding position of the modulation arm in the modulation area (AB) of the switching unit (A11-A14, A21-A24, A31-A34, A41-A44). The narrow rectangular metal hot electrodes and the square external power supply connection leads are connected by wide rectangular metal connecting lines with the same width.

[0012] The substrate layer 1 is made of any one of indium phosphide (InP), gallium arsenide (GaAs), or silicon (Si).

[0013] The material of the lower cladding layer 2 is one of silicon dioxide (SiO2), EpoClad, FSU-8, SU-8, P (MMA-co-GMA), polymethyl methacrylate (PMMA), polyethylene (PE), polyester (PET), and polystyrene (PS).

[0014] The core layer 3 material is one of silicon (Si), FSU-8, SU-8 2002, SU-8 2005, polycarbonate (PC), and polyimide (PI).

[0015] The upper cladding layer 4 is made of one of the following materials: silicon dioxide (SiO2), EpoClad, FSU-8, SU-8, P (MMA-co-GMA), polymethyl methacrylate (PMMA), polyethylene (PE), polyester (PET), or polystyrene (PS). In the same device, the materials of the upper and lower cladding layers can be the same or different. The refractive index of the core layer material must be greater than that of the cladding layer material.

[0016] The electrode 5 is made of an alloy composed of one or more of the following materials: silver, gold, aluminum, and platinum.

[0017] The working principle of the switching units (A11-A14, A21-A24, A31-A34, A41-A44) is as follows: Figure 2As shown in (a), after the signal light enters through the input single straight waveguide, which serves as the input port, it is split into two beams of equal amplitude and phase at the 3-dB coupler (AA) due to inter-waveguide coupling. These beams are then transmitted to the output double straight waveguides on both sides and fed into the two parallel straight waveguides of the modulation region (AB) via the curved coupling waveguide. When no voltage is applied to the electrode above the modulation arm, the two beams of signal light with equal amplitude and phase output from the two parallel straight waveguides are sent to the directional coupling region (AC) via the curved coupling waveguide. Under the inter-waveguide coupling, two beams of signal light with equal amplitude and phase are output along the first and second output ends of the directional coupling region (AC), respectively. The intensities of the two beams of signal light are 1 / 2 of the intensity of the incident signal light from the switching unit. When a voltage U1 is applied to the electrode above the modulation arm, the heat generated by the metal thermoelectrode causes the lower cladding 2, core layer 3, and upper cladding 4 of the modulation arm region to... When the refractive index changes, two signal beams with equal amplitude and a phase difference of π, output from the two parallel straight waveguides of the modulation region (AB), are sent to the directional coupling region (AC) via a bent coupling waveguide. Under the coupling effect between the waveguides, they are output along the first output end of the directional coupling region (AC), and the intensity of the output signal light is consistent with the intensity of the incident signal light of the switching unit. When a voltage U2 is applied to the electrode above the modulation arm, the heat generated by the metal thermoelectrode causes the refractive index of the lower cladding layer 2, core layer 3, and upper cladding layer 4 in the modulation arm region to change. Two signal beams with equal amplitude and a phase difference of -π, output from the two parallel straight waveguides of the modulation region (AB), are sent to the directional coupling region (AC) via a bent coupling waveguide. Under the coupling effect between the waveguides, they are output along the second output end of the directional coupling region (AC), and the intensity of the output signal light is consistent with the intensity of the incident signal light of the switching unit. Thus, the switching function of the three switching states of the switching unit signal is realized.

[0018] The working principle of phase shifters (B11, B12, B21, B22, B31, B32, B41, B42) and cross waveguides (C11-C13, C21-C23, C31-C33, C41-C43) is as follows: Figure 2As shown in (b), since the signal light continues to propagate along the bending direction in the curved cross waveguide, the signal light input from the first input terminal at the top of the cross waveguide (C11-C13, C21-C23, C31-C33, C41-C43) will be output along the second output terminal at the bottom of the cross waveguide (C11-C13, C21-C23, C31-C33, C41-C43), and the signal light input from the second input terminal at the bottom of the cross waveguide (C11-C13, C21-C23, C31-C33, C41-C43) will be output along the second output terminal at the bottom of the cross waveguide (C11-C13, C21-C23, C31-C33, C41-C43). The first output terminal at the top of the waveguides (C13, C21-C23, C31-C33, C41-C43) forms a cross-transmission state. The signal light's phase changes rapidly as it passes through the anti-symmetrical trapezoidal waveguide, causing the phase of the signal light output from the phase shifters (B11, B12, B21, B22, B31, B32, B41, B42) to differ from the phase of the signal light output from a straight waveguide of the same length. The trapezoidal structure length is optimized to match the phase of the signal light output from the cross-waveguides (C11-C13, C21-C23, C31-C33, C41-C43). The working principle of the beam combiners (D11-D14, D21-D24, D31-D34, D41-D44) is as follows: Figure 2 As shown in (c), the signal light with the same or different phase and amplitude input from the phase shifter or cross waveguide passes through the beam combiner (D11-D14, D21-D24, D31-D34, D41-D44), and the signal light intensity output from the output end of the beam combiner is the sum of the input signal light intensity.

[0019] The 4×4 optical waveguide encoder has a minimum input signal light quantity of 1 and a maximum output signal light quantity of 4. In this state, the intensity of a single output signal light is 25% of the intensity of the input signal light. The detection threshold can be set to 20% of the intensity of a single signal light. Exceeding the detection threshold determines the encoding state as 1, and falling below the detection threshold determines the encoding state as 0. Under the action of 16 sets of electrodes, the operation of 16 switching units (A11-A14, A21-A24, A31-A34, A41-A44) is controlled, realizing the optical waveguide encoder function with arbitrary switching capability from the incident light {In1,In2,In3,In4} at the input end to the output end {Out1,Out2,Out3,Out4}. Taking In1 and In4 ports as inputs, when E11, E22, E33, and E44 of the 16 electrode groups are connected to external voltage U2, and E14, E23, E32, and E41 are connected to external voltage U1, the output is from Out1 and Out4 ports. The optical transmission path is as follows: Figure 3 As shown in (a); when electrodes E11, E22, E33, and E44 are connected to external voltage U2, and E14, E23, and E32 are connected to external voltage U1, the output is from ports Out1, Out2, and Out4, as follows. Figure 3 As shown in (b); when electrodes E11, E22, E33, E41, and E44 are connected to external voltage U2, and E14 and E32 are connected to external voltage U1, the output is from ports Out2 and Out4, as follows. Figure 3 As shown in (c).

[0020] The 4×4 optical waveguide encoder described above takes the encoding state with 1 port input as an example (the working principle of single-port input and multi-port input is the same), as shown in Table 1 (0 in the incident end {In1,In2,In3,In4} represents no signal light input, and 1 represents signal light input; 0 in the output end {Out1,Out2,Out3,Out4} represents no signal light output, and 1 represents signal light output; 0 in the electrode unit (E11-E44) represents no external voltage, 1 represents external voltage U1, and 2 represents external voltage U2).

[0021] Compared with existing device structures and fabrication techniques, the advantages of this invention are:

[0022] I. Compared with traditional encoders, the present invention adopts a scheme of multiple cascaded metal hot electrodes, which can greatly simplify the circuit control scheme.

[0023] Second, compared with traditional polymer optical waveguide directional coupling switch arrays, the present invention uses a metal thermoelectrode heating method to control the coupling state, which can reduce the size of the unit structure and improve the integration.

[0024] Appendix Explanation

[0025] Table 1 shows the encoding status of the incident light {In1,In2,In3,In4} of the 4×4 optical waveguide encoder described in this invention as 0001.

[0026] Table 1: Incident light {In1,In2,In3,In4} is encoded as 0001.

[0027] Attached Figure Description

[0028] Figure 1 Figure 1 is a schematic diagram of the structure of the 4×4 optical waveguide encoder of the present invention; Figure 2 is a front view of the 4×4 optical waveguide encoder structure; Figure 3 is a cross-sectional view of position β in Figure 4(a); Figure 4(c) is a top view of the core layer structure of the 4×4 optical waveguide encoder; Figure 5(d) is a top view of the core layer structure of the switching unit; Figure 6(e) is a top view of the phase shifter structure; Figure 7(f) is a top view of the cross waveguide structure; Figure 8(g) is a top view of the beam combiner structure; and Figure 9(h) is a top view of the electrode structure of the 4×4 optical waveguide encoder.

[0029] Figure 2Figure 1 shows the working principle diagram of the 4×4 optical waveguide encoder of the present invention; Figure 2 shows the working principle diagram of the switching unit; Figure 3 shows the working principle diagram of the phase shifter and cross waveguide; Figure 4 shows the working principle diagram of the beam combiner.

[0030] Figure 3 Figure 1 shows the encoding state diagram of the 4×4 optical waveguide encoder described in this invention when the incident light is input through ports In1 and In4; Figure 2 shows the encoding state diagram when E11, E22, E33 and E44 are connected to external voltage U2, and E14, E23, E32 and E41 are connected to external voltage U1; Figure 3 shows the encoding state diagram when E11, E22, E33 and E44 are connected to external voltage U2, and E14, E23 and E32 are connected to external voltage U1; Figure 4 shows the encoding state diagram when E11, E22, E33, E41 and E44 are connected to external voltage U2, and E14 and E32 are connected to external voltage U1.

[0031] Figure 4 Figure (a) is a structural diagram of the core layer of the 4×4 optical waveguide encoder in the application embodiment of the present invention; Figure (b) is a structural diagram of the switching unit; Figure (c) is a structural diagram of the phase shifter; Figure (d) is a structural diagram of the cross waveguide; and Figure (e) is a structural diagram of the beam combiner.

[0032] Figure 5 This is a diagram of the electrode structure of a 4×4 optical waveguide encoder in an application embodiment of the present invention.

[0033] Figure 6 This is a curve showing the relationship between the coupling waveguide length and transmission efficiency of the 3-dB coupler in the application embodiment of the present invention.

[0034] Figure 7 This is a curve showing the relationship between the length of the coupled waveguide in the directional coupling region and the transmission efficiency in the application embodiment described in this invention.

[0035] Figure 8 This is a curve showing the relationship between the temperature of the modulation arm in the voltage-controlled modulation region and the transmission efficiency in an application embodiment of the present invention.

[0036] Figure 9 This is a curve showing the relationship between the length of the curved coupled waveguide and the transmission efficiency in the application embodiment of the present invention.

[0037] Figure 10 This is a curve showing the relationship between the length of the trapezoidal structure of the phase shifter and the transmission efficiency in the application embodiment described in this invention.

[0038] Figure 11 This is a curve showing the relationship between the length of the curved element of the beam combiner and the transmission efficiency in the application embodiment of the present invention.

[0039] Figure 12 This is a schematic diagram of the manufacturing process of an application embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1

[0042] In this embodiment, the substrate layer 1 is made of silicon (Si) with a thickness of 725±15 μm.

[0043] In this embodiment, the lower cladding layer 2 is made of silicon dioxide (SiO2) with a thickness of 5 μm.

[0044] In this embodiment, the core layer 3 material is fluorinated bisphenol A phenolic resin (FSU-8), all adopting a strip structure with a rectangular cross-section, a core layer width of 5 μm, and a thickness of 5 μm; as shown in the attached figure. Figure 4 As shown in Figure a, in this embodiment, the lateral dimension (along the signal light transmission direction) of the core layer 3 of the 4×4 optical waveguide encoder is 33360 μm, the longitudinal dimension (perpendicular to the signal light transmission direction) is 415 μm, and the spacing between adjacent input ports and adjacent output ports is 127 μm. (See attached figure.) Figure 4 As shown in Figure b, the 3-dB couplers (AA) of the switching units (A11-A14, A21-A24, A31-A34, A41-A44) have an input single straight waveguide with a lateral length of 500 μm, an output double straight waveguide with a lateral length of 1880 μm, and a coupling gap of 2 μm for both. The two curved coupled waveguides have a lateral length of 500 μm, and the output port spacing is 34 μm. In the modulation region, the two parallel straight waveguides each have a lateral length of 2000 μm and a longitudinal spacing of 34 μm. In the directional coupling region (AC), the two input curved coupled waveguides have a lateral length of 500 μm and a longitudinal spacing of 34 μm, the two coupled double straight waveguides have a lateral length of 1200 μm, a coupling gap of 2 μm, and the two output curved coupled waveguides have a lateral length of 500 μm and a longitudinal spacing of 34 μm. (See attached figure.) Figure 4As shown in Figure c, the phase shifters (B11, B12, B21, B22, B31, B32, B41, B42) have a lateral length of 1000 μm, the input and output straight waveguides each have a lateral length of 108 μm, the narrow side of the single-sided trapezoidal structure has a longitudinal dimension of 5 μm, the wide side has a longitudinal dimension of 8 μm, and the lateral length of each is 392 μm. (See attached figure) Figure 4 As shown in Figure d, the transverse lengths of the two input and two output ends of the cross waveguides (C11-C13, C21-C23, C31-C33, C41-C43) are all 160 μm, and the longitudinal spacing is 93 μm. The transverse length of the cross structure formed by the two bent coupled waveguides is 680 μm, and the longitudinal spacing is 93 μm. (See attached figure) Figure 4 As shown in Figure e, the two curved coupled waveguides of the combiner (D11-D14, D21-D24, D31-D34, D41-D44) each have a transverse length of 500 μm and a longitudinal spacing of 34 μm. The incident width of the multi-curved flat plate region is 10 μm, the exit width is 5 μm, and the transverse length is 560 μm. The maximum width of the first curved surface is 15 μm, the maximum width of the second curved surface is 12 μm, the width at the cutoff position of the second curved surface is 11 μm, and the minimum width between the two curved surfaces is 10 μm. The surface boundaries satisfy the function y=±x. 2 +b, where b is a function constant, y is defined as the vertical vector length from the boundary line to the center line of the curved structure, and x is defined as the horizontal position of the waveguide structure. The width of the first curved surface increases from 10 μm to 15 μm and then decreases to 11 μm. The origin of the coordinate system is the waveguide center position when the surface width is 15 μm. The upper boundary line satisfies the function y = -x1. 2 +7.5 (- (≤x1≤2), the lower boundary line satisfies the function y=x1 2 -7.5 (- (≤x1≤2); The surface width decreases from 11 μm to 10 μm on the first surface and then increases to 11 μm on the second surface. Taking the waveguide center position when the surface width is 10 μm as the origin of the coordinate system, the upper boundary line satisfies the function y=x2. 2 +5 (-1≤x²≤1), the lower boundary line satisfies the function y=-x² 2 -5 (-1 ≤ x2 ≤ 1); the surface width increases from 11 μm to 12 μm and then decreases back to 11 μm on the second surface. Taking the waveguide center position when the surface width is 12 μm as the origin, the upper boundary line satisfies the function y = -x3. 2 +6 (-1≤x3≤1), the lower boundary line satisfies the function y=x3 2-6 (-1≤x3≤1). The maximum width of the trapezoidal structure connecting the cutoff position of the second curved surface and the output straight waveguide is 11 μm, and the minimum width is 5 μm. The lateral length of the output straight waveguide is 200 μm.

[0045] In this embodiment, the upper cladding layer 3 is made of polymethyl methacrylate (PMMA) with a thickness of 8 μm.

[0046] In this embodiment, electrode 4 is made of aluminum with a thickness of 100 nm; Figure 5 As shown, electrode units (E11, E21, E31, E41) and electrode units (E14, E24, E34, E44) have the same structure and are longitudinally symmetrical; electrode units (E12, E22, E32, E42) and electrode units (E13, E23, E33, E43) have the same structure and are longitudinally symmetrical. The square external power supply connection leads of electrode units (E11, E21, E31, E41, E14, E24, E34, E44) have a lateral length and a longitudinal width of 2000 μm. The narrow rectangular metal thermoelectrodes all have a lateral length of 2000 μm and a longitudinal width of 20 μm. The wide rectangular metal connection lines of electrode units (E11, E21, E31, E41, E14, E24, E34, E44) all have a lateral width of 100 μm and a longitudinal height of 200 μm. The wide rectangular metal connection lines of electrode units (E12, E22, E32, E42, E13, E23, E33, E43) connected to the square external power supply connection leads all have a lateral width of 100 μm and a longitudinal height of 327 μm. The wide rectangular metal connection lines of electrode units (E12, E22, E32, E42, E13, E23, E33, E43) connected to the narrow rectangular metal thermoelectrodes all have a lateral width of 3500 μm and a longitudinal height of 100 μm.

[0047] In this embodiment, a center wavelength of 1550 nm is selected. At this wavelength, the effective refractive index of silicon (Si) is 3.4784, the effective refractive index of silicon dioxide (SiO2) is 1.45, the effective refractive index of fluorinated bisphenol A phenolic resin (FSU-8) is 1.52, and the effective refractive index of polymethyl methacrylate (PMMA) is 1.48.

[0048] This embodiment uses Rsoft software to simulate the effects of different coupling waveguide lengths of the 3-dB coupler (AA) in the switching units (A11-A14, A21-A24, A31-A34, A41-A44), different coupling straight waveguide lengths in the directional coupling region (AC), and different temperatures of the modulation arm controlled by the voltage in the modulation region (AB) on the transmission efficiency. Figure 6 It can be seen that the output light intensity of the 3-dB coupler (AA) is the highest at 49.9% when the coupled waveguide length is 1880 μm, and the coupling length of the 3-dB coupler is 1880 μm. Figure 7 It can be seen that, when two signal beams with the same amplitude and a phase difference of π are input, the output light intensity from the upper port of the directional coupling region (AC) is the largest, reaching 99%, when the length of the coupled straight waveguide in the directional coupling region is 1200 μm, while the output light intensity from the lower port of the directional coupling region (AC) is basically 0, and the coupling length of the directional coupler is 1200 μm. From Figure 8 It can be seen that at room temperature (without external voltage), the output light intensity of the two output ports of the switching units (A11-A14, A21-A24, A31-A34, A41-A44) is equal, realizing the encoding from input terminal 1 to output terminal 11. When the temperature is raised to 296.6 K (corresponding to an external voltage of 2.3 V), the output light intensity of the lower port of the switching units (A11-A14, A21-A24, A31-A34, A41-A44) is the largest, reaching 99.4%, while the upper port of the switching units (A11-A14, A21-A24, A31-A34, A41-A44) has almost no signal light output, realizing the encoding from input terminal 1 to output terminal 01. When the temperature is raised to 299.8 K, the output light intensity of the upper port of the switching units (A11-A14, A21-A24, A31-A34, A41-A44) is the largest, reaching 99.3%. The lower ports of the switching units (A11-A14, A21-A24, A31-A34, A41-A44) have virtually no signal light output, thus enabling the encoding of input terminal 1 to output terminal 10.

[0049] This embodiment uses Rsoft software to simulate the transmission efficiency of the curved coupled waveguide (C11-A43) at different lengths and the output phase of the phase shifters (B11, B12, B21, B22, B31, B32, B41, B42) at different trapezoidal lengths. Figure 9 It can be seen that when the length of the bent coupled waveguide is 680 μm, the output light intensity from the lower port of the cross waveguide (C11-A43) is the largest, reaching 91%, and the length of the bent coupled waveguide in the cross waveguide is 680 μm. Figure 10 It can be seen that when two beams of light with the same phase enter the phase shifter and the cross waveguide respectively, when the trapezoidal length of the phase shifter (B11, B12, B21, B22, B31, B32, B41, B42) is 392 μm, the phase of the light output from the phase shifter is consistent with the phase of the light output from the cross waveguide, thus achieving optical phase compensation.

[0050] This embodiment uses Rsoft software to simulate the output light intensity at different curved unit lengths in the beam combiner (D11-D14, D21-D24, D31-D34, D41-D44) when two in-phase signal beams enter. Figure 11It can be seen that the output light intensity is the largest when the length of the curved unit is 72 μm, reaching 95%; the lateral length of the beam combiner (D11-D14, D21-D24, D31-D34, D41-D44) is 560 μm.

[0051] The manufacturing process of this embodiment is as follows: Figure 12 As shown, in order to better express the process steps, with Figure 1 (a) The section at the modulation arm of section β is used as an example for illustration:

[0052] (1) Spin-coating a 5 μm thick FSU-8 core film 3a onto a silicon dioxide (SiO2) substrate (10 s at a forward rotation rate of 600 r / min and 20 s at a backward rotation rate of 3000 r / min), and then placing it on a heating plate at 65 ℃ for 10 min and 95 ℃ for 20 min.

[0053] (2) Place a photomask 6 with the core layer photolithography pattern on the core layer, and expose the core layer film for 55~65 s using a photolithography machine (60 s in this embodiment), and obtain the designed device pattern on the film surface by photolithography;

[0054] (3) Remove the uncrosslinked core film with developer PGMEA (development time not exceeding 15 s, which can be adjusted according to the development situation) to obtain a core layer 3 with a width of 5 μm. Then, cure the developed device on a heating plate at a temperature of 120 ℃ for 30 min to achieve a hard film effect.

[0055] (4) Apply spin coating process to prepare 8 μm thick polymethyl methacrylate (PMMA) top coating 4 (10 s at a forward rotation rate of 600 r / min and 20 s at a backward rotation rate of 3000 r / min), and place it on a heating plate at 120 ℃ for 30 min after spin coating.

[0056] (5) Use a vacuum coating machine to deposit an aluminum film on the upper cladding layer 4, and spin-coat a BP-212 mask on the aluminum layer at a speed of 2500 r / min for 30 s. Use a photolithography machine to expose the metal layer film for 2~2.5 s (2 s in this embodiment) so that the bottom electrode pattern is displayed on the aluminum metal layer. Use a developer (sodium hydroxide solution, mass ratio of NaOH:H2O=1:200) to remove BP-212 on the electrode surface to obtain electrode 5.

Claims

1. A 4x4 optical waveguide encoder characterized by: From bottom to top, it consists of a substrate (1), a lower cladding layer (2), a core layer (3), an upper cladding layer (4), and electrodes (5). The core layer (3) has a strip-shaped structure. The core layer (3) and the upper cladding layer (4) are located on the upper surface of the lower cladding layer (2), and the core layer (3) is encased in the upper cladding layer (4). The core layer (3) consists of 16 switching units (A11-A14, A21-A24, A31-A34, A41-A44), 8 phase shifter units (B11, B12, B21, B22, B31, B32, B41, B42), and 12 cross waveguide units (C11-C13, C14, C15, C16, C17, C18, C19 ... It consists of C21-C23, C31-C33, C41-C43) and 16 bundle combiner units (D11-D14, D21-D24, D31-D34, D41-D44); respectively labeled as the first switch unit (A11), the second switch unit (A12), the third switch unit (A13), the fourth switch unit (A14), the fifth switch unit (A21), the sixth switch unit (A22), the seventh switch unit (A23), the eighth switch unit (A24), the ninth switch unit (A31), and the tenth switch unit (A44). 32) Eleventh switch unit (A33), twelfth switch unit (A34), thirteenth switch unit (A41), fourteenth switch unit (A42), fifteenth switch unit (A43), sixteenth switch unit (A44); first phase shifter unit (B11), second phase shifter unit (B12), third phase shifter unit (B21), fourth phase shifter unit (B22), fifth phase shifter unit (B31), sixth phase shifter unit (B32), seventh phase shifter unit (B41), eighth phase shifter unit (B42); first crossover Waveguide unit (C11), second cross waveguide unit (C12), third cross waveguide unit (C13), fourth cross waveguide unit (C21), fifth cross waveguide unit (C22), sixth cross waveguide unit (C23), seventh cross waveguide unit (C31), eighth cross waveguide unit (C32), ninth cross waveguide unit (C33), tenth cross waveguide unit (C41), eleventh cross waveguide unit (C42), twelfth cross waveguide unit (C43); first beam combiner unit (D11), second beam combiner unit (D12) The following units are listed: third bundle combiner unit (D13), fourth bundle combiner unit (D14), fifth bundle combiner unit (D21), sixth bundle combiner unit (D22), seventh bundle combiner unit (D23), eighth bundle combiner unit (D24), ninth bundle combiner unit (D31), tenth bundle combiner unit (D32), eleventh bundle combiner unit (D33), twelfth bundle combiner unit (D34), thirteenth bundle combiner unit (D41), fourteenth bundle combiner unit (D42), fifteenth bundle combiner unit (D43), and sixteenth bundle combiner unit (D44).The first switching unit (A11), the second switching unit (A12), the third switching unit (A13), the fourth switching unit (A14), the first phase shifter unit (B11), the second phase shifter unit (B12), the first cross waveguide unit (C11), the second cross waveguide unit (C12), the third cross waveguide unit (C13), the first combiner unit (D11), the second combiner unit (D12), the third combiner unit (D13), and the fourth combiner unit (D14) constitute the first 4×4 optical waveguide encoder; the fifth switching unit (A21) The sixth switch unit (A22), the seventh switch unit (A23), the eighth switch unit (A24), the third phase shifter unit (B21), the fourth phase shifter unit (B22), the fourth cross waveguide unit (C21), the fifth cross waveguide unit (C22), the sixth cross waveguide unit (C23), the fifth combiner unit (D21), the sixth combiner unit (D22), the seventh combiner unit (D23), and the eighth combiner unit (D24) constitute the second 4×4 optical waveguide encoder; the ninth switch unit (A31) and the tenth switch unit (A32) The eleventh switch unit (A33), the twelfth switch unit (A34), the fifth phase shifter unit (B31), the sixth phase shifter unit (B32), the seventh cross waveguide unit (C31), the eighth cross waveguide unit (C32), the ninth cross waveguide unit (C33), the ninth beam combiner unit (D31), the tenth beam combiner unit (D32), the eleventh beam combiner unit (D33), and the twelfth beam combiner unit (D34) constitute the third 4×4 optical waveguide encoder; the thirteenth switch unit (A41), the fourteenth switch unit (A42), and the fifteenth... The switching unit (A43), the sixteenth switching unit (A44), the seventh phase shifter unit (B41), the eighth phase shifter unit (B42), the tenth cross waveguide unit (C41), the eleventh cross waveguide unit (C42), the twelfth cross waveguide unit (C43), the thirteenth combiner unit (D41), the fourteenth combiner unit (D42), the fifteenth combiner unit (D43), and the sixteenth combiner unit (D44) constitute the fourth 4×4 optical waveguide encoder; the first to fourth 4×4 optical waveguide encoders are connected in sequence to form a 4×4 optical waveguide encoder; The first switching unit (A11), second switching unit (A12), third switching unit (A13), fourth switching unit (A14), fifth switching unit (A21), sixth switching unit (A22), seventh switching unit (A23), eighth switching unit (A24), ninth switching unit (A31), tenth switching unit (A32), eleventh switching unit (A33), twelfth switching unit (A34), thirteenth switching unit (A41), fourteenth switching unit (A42), fifteenth switching unit (A43), and sixteenth switching unit (A44) have the same structure, consisting of three parts: a 3-dB coupler (AA), a modulation region (AB), and a directional coupling region (AC); the modulation region (AB) is composed of... The system consists of two parallel straight waveguides, with the straight waveguide on the right side of the optical transmission direction serving as the modulation arm. An electrode (5) is provided on the upper surface of the upper cladding (4) corresponding to its position. The 3-dB coupler (AA) consists of an input single straight waveguide and an output double straight waveguide with curved coupling waveguides at the ends. The input single straight waveguide and the output double straight waveguide are parallel to each other. The output double straight waveguides are of the same size and are symmetrically arranged on both sides of the input single straight waveguide. The ends of the output double straight waveguides are extended to both sides through curved coupling waveguides and are connected to the two parallel straight waveguides of the modulation region (AB). The directional coupling region (AC) consists of double straight waveguides with curved coupling waveguides at both ends. The double straight waveguides are of the same size and are parallel to each other. Their ends are extended to both sides through curved coupling waveguides and are connected to the two parallel straight waveguides of the modulation region (AB). The two parallel straight waveguides in the control region (AB) are connected to each other, and their ends are extended to both sides through curved coupling waveguides to form the first output terminal and the second output terminal; the spacing between the two straight waveguides in the directional coupling region (AC) is small, forming a directional coupling structure; the first phase shifter unit (B11), the second phase shifter unit (B12), the third phase shifter unit (B21), the fourth phase shifter unit (B22), the fifth phase shifter unit (B31), the sixth phase shifter unit (B32), the seventh phase shifter unit (B41), and the eighth phase shifter unit (B42) have the same structure, which are sequentially composed of an input straight waveguide, two symmetrically arranged trapezoidal waveguides, and an output straight waveguide connected together. The width of the two symmetrically arranged trapezoidal waveguides first widens and then... Narrowing; the first cross waveguide unit (C11), the second cross waveguide unit (C12), the third cross waveguide unit (C13), the fourth cross waveguide unit (C21), the fifth cross waveguide unit (C22), the sixth cross waveguide unit (C23), the seventh cross waveguide unit (C31), the eighth cross waveguide unit (C32), the ninth cross waveguide unit (C33), the tenth cross waveguide unit (C41), the eleventh cross waveguide unit (C42), and the twelfth cross waveguide unit (C43) have the same structure, consisting of two waveguides connected in a cross manner, forming a first input end, a second input end, a first output end, and a second output end. The first input end and the second input end are parallel to each other, and the first output end and the second output end are parallel to each other;The first bundle combiner unit (D11), the second bundle combiner unit (D12), the third bundle combiner unit (D13), the fourth bundle combiner unit (D14), the fifth bundle combiner unit (D21), the sixth bundle combiner unit (D22), the seventh bundle combiner unit (D23), the eighth bundle combiner unit (D24), the ninth bundle combiner unit (D31), the tenth bundle combiner unit (D32), the eleventh bundle combiner unit (D33), the twelfth bundle combiner unit (D34), the thirteenth bundle combiner unit (D41), the fourteenth bundle combiner unit (D42), the fifteenth bundle combiner unit (D43), and the sixteenth bundle combiner unit (D44) have the same structure. A symmetrical multi-surface structure is constructed by sequentially connecting two curved coupled waveguides, a first curved waveguide, a second curved waveguide, a trapezoidal waveguide, and a straight waveguide. The two curved coupled waveguides form the first and second input terminals of the beam combiner unit, while the straight waveguide forms the output terminal. The surface width of the beam combiner unit varies exponentially, first increasing and then decreasing to form the first surface, then increasing and then decreasing again to form the second surface. Finally, the trapezoidal waveguide connects the second curved waveguide and the straight waveguide to control the diffraction order, thus achieving the function of a logic OR gate. This 4×4 optical waveguide encoder has four input ports (In1~In4) and four output ports (Out1~Out4).

2. A 4 x 4 optical waveguide encoder as claimed in claim 1, characterized in that: In the first 4×4 optical waveguide encoder, the input straight waveguide of the first phase shifter (B11) is connected to the first output terminal of the directional coupling region (AC) of the first switching unit (A11), and the output straight waveguide of the first phase shifter (B11) is connected to the first input terminal of the first beam combiner (D11). The input straight waveguide of the second phase shifter (B12) is connected to the second output terminal of the directional coupling region (AC) of the fourth switching unit (A14), and the output straight waveguide of the second phase shifter (B12) is connected to the second input terminal of the fourth beam combiner (D14); the first input terminal of the first cross waveguide (C11) is connected to the second output terminal of the directional coupling region (AC) of the first switching unit (A11), the second input terminal of the first cross waveguide (C11) is connected to the first output terminal of the directional coupling region (AC) of the second switching unit (A12), the first output terminal of the first cross waveguide (C11) is connected to the second input terminal of the first beam combiner (D11), and the second output terminal of the first cross waveguide (C11) is connected to the second beam combiner (D11). The first input terminal of the second cross waveguide (C12) is connected to the first input terminal of the second cross waveguide (C12); the first input terminal of the second cross waveguide (C12) is connected to the second output terminal of the directional coupling region (AC) of the second switching unit (A12); the second input terminal of the second cross waveguide (C12) is connected to the first output terminal of the directional coupling region (AC) of the third switching unit (A13); the first output terminal of the second cross waveguide (C12) is connected to the second input terminal of the second beam combiner (D12); the second output terminal of the second cross waveguide (C12) is connected to the first input terminal of the third beam combiner (D13); the first input terminal of the third cross waveguide (C13) is connected to the second output terminal of the directional coupling region (AC) of the third switching unit (A13); the third ... second output terminal of the third cross waveguide (C12) is connected to the second input terminal of the The second input terminal of the third cross waveguide (C13) is connected to the first output terminal of the directional coupling region (AC) of the fourth switch unit (A14). The first output terminal of the third cross waveguide (C13) is connected to the second input terminal of the third combiner (D13). The second output terminal of the third cross waveguide (C13) is connected to the first input terminal of the fourth combiner (D14). The signal light after being combined by the first combiner unit (D11), the second combiner unit (D12), the third combiner unit (D13), and the fourth combiner unit (D14) is used as the input signal of the second 4×4 optical waveguide encoder, and so on. The signal light input at the first input terminal of the section will be output along the second output terminal at the bottom of the cross waveguide (C11-C13, C21-C23, C31-C33, C41-C43), and the signal light input at the second input terminal at the bottom of the cross waveguide (C11-C13, C21-C23, C31-C33, C41-C43) will be output along the first output terminal at the top of the cross waveguide (C11-C13, C21-C23, C31-C33, C41-C43), forming a cross transmission state; by optimizing the length of the trapezoidal structure to make it phase-matched with the signal light output from the output terminal of the cross waveguide (C11-C13, C21-C23, C31-C33, C41-C43);Signal beams with the same or different phases and amplitudes input from the phase shifter or cross waveguide pass through the combiner (D11-D14, D21-D24, D31-D34, D41-D44). The intensity of the signal beam output from the combiner is the sum of the intensity of the input signal beams.

3. A 4×4 optical waveguide encoder as described in claim 1, characterized in that: The electrode (5) consists of 16 electrode units (E11-E14, E21-E24, E31-E34, E41-E44). Each electrode unit consists of two square external power supply connection leads, one narrow rectangular metal hot electrode and two wide rectangular metal connecting lines, which act on the modulation arm of the modulation area (AB) of the switching unit (A11-A14, A21-A24, A31-A34, A41-A44). The square external power supply connection leads are evenly distributed on both sides of the 4×4 optical waveguide encoder. The narrow rectangular metal hot electrode is arranged on the surface of the cladding (4) at the corresponding position of the modulation arm in the modulation area (AB) of the switching unit (A11-A14, A21-A24, A31-A34, A41-A44). The narrow rectangular metal hot electrode and the square external power supply connection leads are connected by the wide rectangular metal connecting lines. The width of the metal connecting lines is consistent.

4. A 4 x 4 optical waveguide encoder as claimed in claim 1, characterized in that: The substrate (1) is made of any one of indium phosphide, gallium arsenide, and silicon; the lower cladding (2) is made of one of silicon dioxide, EpoClad, FSU-8, SU-8, P(MMA-co-GMA), polymethyl methacrylate, polyethylene, polyester, and polystyrene; the core layer (3) is made of one of silicon, FSU-8, SU-8 2002, SU-8 2005, polycarbonate, and polyimide; the upper cladding (4) is made of one of silicon dioxide, EpoClad, FSU-8, SU-8, P(MMA-co-GMA), polymethyl methacrylate, polyethylene, polyester, and polystyrene; and the electrode (5) is made of an alloy composed of one or more of silver, gold, aluminum, and platinum.

5. A 4 x 4 optical waveguide encoder as claimed in claim 1, characterized in that: After the signal light enters through the input single straight waveguide (which serves as the input port), it is split into two beams of equal amplitude and phase at the 3-dB coupler (AA) due to inter-waveguide coupling. These beams are then transmitted to the output double straight waveguides on both sides and fed into the two parallel straight waveguides of the modulation region (AB) via the curved coupling waveguide. When no voltage is applied to the electrodes above the modulation arm, the two beams of signal light with equal amplitude and phase output from the two parallel straight waveguides are sent to the directional coupling region (AC) via the curved coupling waveguide. Under the inter-waveguide coupling, beams of equal amplitude and phase are output along the first and second output terminals of the directional coupling region (AC). Two signal beams with the same position, the intensity of the two signal beams is 1 / 2 of the intensity of the incident signal beam of the switching unit; when a voltage U1 is applied to the electrode above the modulation arm, the heat generated by the metal hot electrode causes the refractive index of the lower cladding (2), core layer (3) and upper cladding (4) of the modulation arm region to change. Two signal beams with equal amplitude and phase difference π output from the two parallel straight waveguides of the modulation region (AB) are sent to the directional coupling region (AC) through the bent coupling waveguide. Under the coupling effect between the waveguides, they are output along the first output end of the directional coupling region (AC), and the intensity of the output signal beam is consistent with the intensity of the incident signal beam of the switching unit. When a voltage U2 is applied to the electrode above the modulation arm, the heat generated by the metal thermoelectrode causes the refractive index of the lower cladding (2), core layer (3), and upper cladding (4) of the modulation arm region to change. Two signal beams with equal amplitude and a phase difference of -π are output from the two parallel straight waveguides of the modulation region (AB) and sent to the directional coupling region (AC) through the bent coupling waveguide. Under the coupling effect between the waveguides, the signal beams are output along the second output end of the directional coupling region (AC). The intensity of the output signal beams is consistent with the intensity of the incident signal beams of the switching unit; thereby realizing the switching function of the three switching states of the switching unit signal.

6. A 4 x 4 optical waveguide encoder according to any one of claims 1 to 5, wherein: The substrate layer (1) has a thickness of 725±15 μm, the lower cladding layer (2) has a thickness of 5 μm, the upper cladding layer (3) has a thickness of 8 μm, and the core layer (3) has a width and thickness of 5 μm; the electrode (5) has a thickness of 100 nm; the electrode units (E11, E21, E31, E41) and the electrode units (E14, E24, E34, E44) have the same structure and are longitudinally symmetrical; the electrode units (E12, E22, E32, E42) and the electrode units (E13, E23, E33, E43) have the same structure and are longitudinally symmetrical; the lateral length and longitudinal width of the square external power supply connection lead are both 2000 μm, and the lateral length of the narrow rectangular metal hot electrode is 2000 μm and the longitudinal width is 2000 μm. The transverse width of the wide rectangular metal connecting lines of the electrode units (E11, E21, E31, E41, E14, E24, E34, E44) connected to the square external power supply connection leads is 100 μm, and the longitudinal height is 200 μm. The transverse width of the wide rectangular metal connecting lines of the electrode units (E12, E22, E32, E42, E13, E23, E33, E43) connected to the square external power supply connection leads is 100 μm, and the longitudinal height is 327 μm. The transverse width of the wide rectangular metal connecting lines of the electrode units (E12, E22, E32, E42, E13, E23, E33, E43) connected to the narrow rectangular metal thermoelectrodes is 3500 μm, and the longitudinal height is 100 μm.

7. A 4×4 optical waveguide encoder as described in any one of claims 1 to 5, characterized in that: The core layer (3) has a lateral dimension of 33360 μm along the signal light transmission direction and a longitudinal dimension of 415 μm perpendicular to the signal light transmission direction. The spacing between adjacent input ports and adjacent output ports is 127 μm. The input single straight waveguide of the 3-dB coupler (AA) of the switching unit (A11-A14, A21-A24, A31-A34, A41-A44) has a lateral length of 500 μm, the output double straight waveguide has a lateral length of 1880 μm, and the coupling gap is 2 μm. The two curved coupled waveguides have a lateral length of 500 μm, and the output port spacing is 34 μm. The two parallel straight waveguides in the modulation region have a lateral length of 2000 μm and a longitudinal spacing of 34 μm. The two input curved coupled waveguides in the directional coupling region (AC) have a lateral length of 500 μm and a longitudinal spacing of 34 μm. The two coupled double straight waveguides have a lateral length of 1200 μm and a coupling gap of 2 μm. μm, the two output curved coupling waveguides have a transverse length of 500 μm and a longitudinal spacing of 34 μm; The phase shifters (B11, B12, B21, B22, B31, B32, B41, B42) have a lateral length of 1000 μm, and the input and output straight waveguides each have a lateral length of 108 μm. The narrow side of each single-sided trapezoidal structure has a longitudinal dimension of 5 μm, the wide side has a longitudinal dimension of 8 μm, and the lateral length is 392 μm. The cross waveguides (C11-C13, C21-C23, C31-C33, C41-C43) each have a lateral length of 160 μm at both input and output ends, and a longitudinal spacing of 93 μm. The cross structure formed by two bent coupling waveguides each has a lateral length of 680 μm and a longitudinal spacing of 93 μm. The combiners (D11-D14, D21-D24, D31-D34, D41-D44) each have two bent coupling waveguides with a lateral length of 500 μm and a longitudinal spacing of 34 μm. The incident width of the multi-curved flat plate region is 10 μm, the width of the straight waveguide at the exit end is 5 μm, the lateral length is 560 μm, the maximum width of the first curved surface is 15 μm, the maximum width of the second curved surface is 12 μm, the width at the cutoff position of the second curved surface is 11 μm, and the minimum width between the two curved surfaces is 10 μm; the surface boundaries satisfy the function y=±x 2 +b, where b is a function constant, y is defined as the vertical vector length from the boundary line to the center line of the curved structure, and x is defined as the horizontal position of the waveguide structure; the width of the first curved surface increases from 10 μm to 15 μm and then decreases to 11 μm, with the center position of the waveguide when the surface width is 15 μm as the origin of the coordinate system, and the upper boundary line satisfies the function y = -x1. 2 +15 (- (≤x1≤2), the lower boundary line satisfies the function y=x1 2 -15 (- (≤x1≤2); The surface width decreases from 11 μm to 10 μm on the first surface and then increases to 11 μm on the second surface. Taking the waveguide center position when the surface width is 10 μm as the origin of the coordinate system, the upper boundary line satisfies the function y=x2. 2 +10 (-1≤x²≤1), the lower boundary line satisfies the function y=-x² 2 -10 (-1≤x2≤1); the surface width increases from 11 μm to 12 μm and then decreases back to 11 μm on the second surface. Taking the waveguide center position when the surface width is 12 μm as the origin, the upper boundary line satisfies the function y=-x3. 2 +12 (-1≤x3≤1), the lower boundary line satisfies the function y=x3 2 -12 (-1≤x3≤1); the maximum width of the trapezoidal structure connecting the cutoff position of the second curved surface and the output straight waveguide is 11 μm, and the minimum width is 5 μm; the transverse length of the output straight waveguide is 200 μm.

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