Dual-arm tunable 2x2 thermo-optic switch with phase shifter

Abstract

A double-arm adjustable 2*2 thermo-optic switch with phase shifter belongs to the technical field of optical communication. The switch is composed of a silicon substrate, a silicon dioxide lower cladding layer, a polymer waveguide core layer and a polymer upper cladding layer. The polymer waveguide core layer is of MZI type structure, which is composed of two input waveguides, an input 2*2 multimode interference coupler, two input S-bent waveguides, a phase shifter, a straight waveguide, a first modulation arm waveguide and a second modulation arm waveguide, two output S-bent waveguides, an output 2*2 multimode interference coupler and two output waveguides. The two modulation arm waveguides are parallel to each other. Two metal electrodes parallel to each other are arranged on the polymer upper cladding layer at the positions of the two modulation arm waveguides. The phase shifter pre-introduces a pi / 2 phase shift for the first modulation arm waveguide. Each modulation arm waveguide only needs to introduce a pi / 2 phase shift to realize the state change of the switch, thereby realizing the function of the double-arm adjustable 2*2 thermo-optic switch and reducing the power consumption required for single modulation.

Description

Technical Field

[0001] This invention belongs to the field of optical communication technology, specifically relating to a dual-arm adjustable 2×2 thermo-optical switch with a phase shifter. Background Technology

[0002] With the rapid development of information technology and the increasing demand for high-speed, high-bandwidth communication, optical communication, as a high-speed, high-capacity, and low-power communication method, has been widely used. In optical communication systems, optical switches, as one of the core components, are used to control the routing of optical signals. Currently, thermo-optical switches, as a common optical switching technology, are widely used in optical communication systems. Because they are suitable for large-scale production, integrated optical switch arrays have been extensively studied. Most current thermo-optical switches operate by modulating individual modulation arms, causing a π-phase change in the light passing through a single modulation arm. As the number of interconnecting ports gradually increases, simultaneous operation of switches generates extremely high power consumption and thermal crosstalk to surrounding switches, potentially even causing array failure. Therefore, to achieve low-power, large-scale optical switch arrays, a low-power thermo-optical switch is urgently needed. Summary of the Invention

[0003] To address the aforementioned problems in the prior art, this invention proposes a dual-arm adjustable 2×2 thermo-optical switch with a phase shifter.

[0004] like Figure 1 and Figure 5As shown, the dual-arm adjustable 2×2 thermo-optic switch with phase shifter described in this invention is composed of a silicon substrate (1), a silicon dioxide lower cladding (2), a polymer waveguide core layer (3), and a polymer upper cladding (4) from bottom to top. The polymer waveguide core layer (3) and the polymer upper cladding (4) are located on the silicon dioxide lower cladding (2), and the polymer waveguide core layer (3) is completely covered by the polymer upper cladding (4). The polymer waveguide core layer (3) is an MZI type structure, consisting of a first input waveguide (101) and a second input waveguide (102) with the same structure and size and symmetrical design, and an input 2×2 multimode... The system comprises an interference coupler (300), a first input S-bend waveguide (103) and a second input S-bend waveguide (103') of identical and symmetrical structure and size, a phase shifter (500), a straight waveguide (109), a first modulation arm waveguide (104) and a second modulation arm waveguide (105) of identical and symmetrical structure and size, a first output S-bend waveguide (106) and a second output S-bend waveguide (106') of identical and symmetrical structure and size, an output 2×2 multimode interference coupler (400), and a first output waveguide (107) and a second output waveguide (108) of identical and symmetrical structure and size. The first modulation arm waveguide (104) and the second modulation arm waveguide (105) are parallel to each other, and a first metal electrode (201) and a second metal electrode (202) are disposed parallel to each other on the polymer cladding (4) at the locations of the first modulation arm waveguide (104) and the second modulation arm waveguide (105). The first input waveguide (101) and the second input waveguide (102) serve as the first input channel (Input1) and the second input channel (Input2), respectively; the first output waveguide (107) and the second output waveguide (108) serve as the first output channel (Output1) and the second output channel (Output2), respectively; each S-bend waveguide is composed of two circular arcs of the same size and centrally symmetrical, which are connected together to form an "S-bend" shape;

[0005] like Figure 2 As shown, the input 2×2 multimode interference coupler (300) and the output 2×2 multimode interference coupler (400) have the same structure; the input 2×2 multimode interference coupler (300) consists of a first input wedge waveguide (301) and a second input wedge waveguide (302) with the same structure and size and symmetrical, a first multimode interference region (303), a first output wedge waveguide (304) and a second output wedge waveguide (305) with the same structure and size and symmetrical; the output 2×2 multimode interference coupler (400) consists of a third input wedge waveguide (301') and a fourth input wedge waveguide (302') with the same structure and size and symmetrical, a second multimode interference region (303'), a third output wedge waveguide (304') and a fourth output wedge waveguide (305') with the same structure and size and symmetrical;

[0006] The first input waveguide (101) is connected to the first input wedge waveguide (301), the first output wedge waveguide (304) is connected to the first input S-bend waveguide (103), the phase shifter (500), the first modulation arm waveguide (104), the first output S-bend waveguide (106) and the third input wedge waveguide (301') in sequence, and the third output wedge waveguide (304') is connected to the first output waveguide (107); the second input waveguide (102) is connected to the second input wedge waveguide (302), the second output wedge waveguide (305) is connected to the second input S-bend waveguide (103'), the straight waveguide (109), the second modulation arm waveguide (105), the second output S-bend waveguide (106') and the fourth input wedge waveguide (302') in sequence, and the fourth output wedge waveguide (305') and the second output waveguide (108) in sequence;

[0007] The working principle of the dual-arm adjustable 2×2 thermo-optical switch with phase shifter described in this invention is as follows:

[0008] The input light is fed into either the first input waveguide (101) or the second input waveguide (102), and then enters the input 2×2 multimode interference coupler (300), where it is split into two beams of completely equal power. One beam undergoes a π / 2 phase shift via a phase shifter (500), while the other beam passes through a straight waveguide (109) without phase shift, and then enters the first modulation arm waveguide (104) and the second modulation arm waveguide (105) respectively. The beams then pass through the first output S-bend waveguide (106) and the second output S-bend waveguide (105) respectively. The S-curved waveguide (106') enters the output 2×2 multimode interference coupler (400). When no voltage is applied to either the first modulation arm waveguide (104) or the second modulation arm waveguide (105) (i.e., there is no temperature difference between the two modulation arm waveguides), the phase difference between the two beams entering the output 2×2 multimode interference coupler (400) is π / 2, and the output light intensities of the output channels (Output1) and (Output2) are equal, both being half of the maximum light intensity. When a voltage is applied to the metal electrode for modulation (i.e., the two modulation arm waveguides are heated), due to the thermo-optic effect, the refractive index of the polymer modulation arm waveguide changes with increasing temperature, which in turn causes a phase change in the signal light in the polymer modulation arm waveguide when it reaches the output 2×2 multimode interference coupler (400). We denote the phase difference of the signal light before and after the voltage is applied as Δφ. n(n represents the nth modulation arm waveguide, n = 1 or 2). When light enters from the input channel (Input1), if only the first metal electrode (201) is energized, the phase change caused by the applied voltage is negative because the thermo-optic coefficient of the polymer material is negative. When the phase difference Δφ1 = -π / 2 of the signal light before and after the voltage is applied in the first modulation arm waveguide (104), the phase difference between the two beams of light entering the output 2×2 multimode interference coupler (400) is π / 2 + (-π / 2) = 0, and the light will be output from the output channel (Output2), i.e., the phase difference is π / 2 + (-π / 2) = 0. When operating in the Cross state, the output light intensity is the same as the input light intensity. When only the second metal electrode (202) is applied with voltage, the phase difference Δφ2=-π / 2 of the signal light before and after the voltage is applied in the second modulation arm waveguide (105) is π / 2-(-π / 2)=π. At this time, the phase difference of the two beams of light entering the output 2×2 multimode interference coupler (400) is π / 2-(-π / 2)=π. The light will be output from the output channel (Output1), that is, operating in the Bar state, the output light intensity is the same as the input light intensity, thus realizing the function of switching the two channels. When light enters through the input channel (Input2), if only the first metal electrode (201) is energized, and the phase difference Δφ1 = -π / 2 of the signal light before and after the voltage is applied in the first modulation arm waveguide (104), then the phase difference between the two beams of light entering the output 2×2 multimode interference coupler (400) is π / 2 + (-π / 2) = 0, and the light is output from the output channel (Output1), i.e., it is working in the Cross state, and the output light intensity is the same as the input light intensity; when only the second metal electrode (202) is energized, and the phase difference Δφ2 = -π / 2 of the signal light before and after the voltage is applied in the second modulation arm waveguide (105), then the phase difference between the two beams of light entering the output 2×2 multimode interference coupler (400) is π / 2 - (-π / 2) = π, and the light is output from the output channel (Output2), i.e., it is working in the Bar state, and the output light intensity is the same as the input light intensity; thus realizing the dual-arm adjustable 2×2 thermo-optical switch function.

[0009] When one of the modulation arm waveguides in the MZI structure is heated, the refractive index of the modulation arm waveguide changes, causing a change in the phase of the beam in the modulation arm waveguide. This change is then converted into a change in optical amplitude through coupling and interference of the two arm beams. When the introduced phase shift reaches π, the switching state can be changed. To further reduce the power consumption required for the thermo-optical switch, this invention introduces a π / 2 phase shifter (500) in the first modulation arm waveguide (104). The phase shifter (500) consists of an input wedge waveguide (501) and an output wedge waveguide (502). The main principle is to modulate the phase of the optical signal by changing the optical path in the optical waveguide. The phase shifter (500) pre-introduces a π / 2 phase shift into the first modulation arm waveguide (104). By modulating the two modulation arm waveguides, each modulation arm waveguide only needs to introduce a π / 2 phase shift to change the switching state, thereby changing the switching operation state and reducing the power consumption required for a single modulation.

[0010] The innovation of this invention compared to existing technologies lies in:

[0011] 1. Due to the introduction of the π / 2 phase shifter, only a π / 2 phase shift is required for each modulation, which reduces the power consumption required for a single modulation;

[0012] 2. Due to the introduction of the π / 2 phase shifter, only a π / 2 phase shift is required for each modulation, which reduces crosstalk of individual switches and facilitates large-scale integration;

[0013] 3. Due to the introduction of the π / 2 phase shifter, only a π / 2 phase shift is required for each modulation, which reduces the amount of refractive index change in a single modulation arm waveguide, thereby reducing polarization-dependent loss caused by refractive index changes and facilitating large-scale integration. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 : Schematic diagram of the 2×2MZI thermo-optical switch polymer waveguide core and modulation electrode structure described in this invention;

[0016] Figure 2 : Schematic diagram of the 2×2 multimode interference coupler structure described in this invention;

[0017] Figure 3 : A schematic diagram of the phase shifter (500) of the present invention;

[0018] Figure 4 Optical field transmission diagram of the 2×2 multimode interference coupler (300) described in this invention;

[0019] Figure 5 : A schematic diagram of the cross-section of the 2×2 thermo-optical switch described in this invention;

[0020] Figure 6 The transmission optical field diagrams of the 2×2 thermo-optic switch described in this invention are as follows: (a) is a simulated optical field diagram when no voltage is applied to any metal electrode; (b) is a simulated optical field diagram when only the first modulation arm waveguide (104) is subjected to voltage, causing a temperature change of 1.02564K in the modulation arm waveguide; and (c) is a simulated optical field diagram when only the second modulation arm waveguide (105) is subjected to voltage, causing a temperature change of 1.02564K in the modulation arm waveguide.

[0021] Figure 7 The following is a simulation result of the switching characteristics of the output channels Output1 and Output2 when the 2×2 thermo-optic switch of the present invention applies a voltage to the first modulation arm waveguide (104) to cause a temperature change of 1.02564K in the modulation arm waveguide;

[0022] Figure 8 The following is a simulation result of the switching characteristics of the output channels Output1 and Output2 when the 2×2 thermo-optic switch of the present invention applies a voltage to the second modulation arm waveguide (105) to cause a temperature change of 1.02564K in the modulation arm waveguide;

[0023] Figure 9 : Flowchart of the fabrication process of the 2×2 thermo-optical switch described in this invention. Detailed Implementation

[0024] To further illustrate the core technical solution and application objectives of this invention, the following description is provided in conjunction with the accompanying drawings and embodiments. However, it is worth noting that the scope of this invention is not limited to the embodiments mentioned herein.

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] As attached Figure 1 and Figure 5As shown, the dual-arm adjustable 2×2 thermo-optic switch with phase shifter described in this invention is composed of a silicon substrate (1), a silicon dioxide lower cladding (2), a polymer waveguide core layer (3), and a polymer upper cladding (4) from bottom to top. The polymer waveguide core layer (3) and the polymer upper cladding (4) are located on the silicon dioxide lower cladding (2), and the polymer waveguide core layer (3) is completely covered by the polymer upper cladding (4). The polymer waveguide core layer (3) is an MZI type structure, consisting of a first input waveguide (101) and a second input waveguide (102) of the same structure and size and symmetrical, an input 2×2 multimode interference coupler (300), a first input S-bend waveguide (103) and a second input S-bend waveguide (103') of the same structure and size and symmetrical, and a phase shifter. The device comprises a shifter (500), a straight waveguide (109), a first modulation arm waveguide (104) and a second modulation arm waveguide (105) with the same structure and size and symmetrical, a first output S-bend waveguide (106) and a second output S-bend waveguide (106') with the same structure and size and symmetrical, an output 2×2 multimode interference coupler (400), and a first output waveguide (107) and a second output waveguide (108) with the same structure and size and symmetrical; wherein, the first modulation arm waveguide (104) and the second modulation arm waveguide (105) are parallel to each other, and a first metal electrode (201) and a second metal electrode (202) are disposed on the polymer cladding (4) at the location of the first modulation arm waveguide (104) and the second modulation arm waveguide (105). The first input waveguide (101) and the second input waveguide (102) serve as the first input channel (input1) and the second input channel (input2), respectively. The first output waveguide (107) and the second output waveguide (108) serve as the first output channel (output1) and the second output channel (output2), respectively. Each S-bend waveguide consists of two circular arcs of the same size and central symmetry, which are connected together to form an "S-bend" shape. Taking into account the relationship between modulation efficiency and size, the lengths of the first modulation arm waveguide (104) and the second modulation arm waveguide (105) are set to 2000 μm.

[0028] As attached Figure 2 As shown in (a), this is a schematic diagram of the input 2×2 multimode interference coupler (300) of the present invention; as attached Figure 2(b) shows a schematic diagram of the output 2×2 multimode interference coupler (400) of the present invention; the input 2×2 multimode interference coupler (300) consists of a first input wedge waveguide (301) and a second input wedge waveguide (302) with the same structure and size and symmetrical, a first multimode interference region (303), a first output wedge waveguide (304) and a second output wedge waveguide (305) with the same structure and size and symmetrical; the output 2×2 multimode interference coupler (400) consists of a third input wedge waveguide with the same structure and size and symmetrical. The system comprises a waveguide (301'), a fourth input wedge waveguide (302'), a second multimode interference region (303'), and two symmetrical output wedge waveguides (304' and 305') with identical structure and size. In this embodiment, considering both device size and actual fabrication difficulty, the system consists of a first input wedge waveguide (301'), a second input wedge waveguide (302'), a first output wedge waveguide (304'), a second output wedge waveguide (305'), a third input wedge waveguide (301'), and a fourth input wedge waveguide (305'). The lengths of the first input wedge waveguide (302'), the third output wedge waveguide (304'), and the fourth output wedge waveguide (305') are 13.5 μm. The widths of the first input wedge waveguide (301'), the second input wedge waveguide (302'), the third input wedge waveguide (301'), and the fourth input wedge waveguide (302') vary linearly from 4 μm to 5 μm. The widths of the first output wedge waveguide (304'), the second output wedge waveguide (305'), the third output wedge waveguide (304'), and the fourth output wedge waveguide (305') vary from... The waveguide width linearly changes from 5 μm to 4 μm. The center-to-center spacing of the first input wedge waveguide (301), the second input wedge waveguide (302), the first output wedge waveguide (304), the second output wedge waveguide (305), the third input wedge waveguide (301'), the fourth input wedge waveguide (302'), the third output wedge waveguide (304'), and the fourth output wedge waveguide (305') is 15 μm. The width of the first multimode interference region (303) and the second multimode interference region (303') is 20 μm, and the length is 871 μm. The input 2×2 multimode interference coupler (400) and the output 2×2 multimode interference coupler (300) of the present invention have the same structural dimensions.

[0029] As attached Figure 3 The diagram shown is a schematic representation of the phase shifter (500) of this invention. From left to right, the components are an input wedge waveguide (501) and an output wedge waveguide (502). Both the input wedge waveguide (501) and the output wedge waveguide (502) have a length of 90 μm. The width of the input wedge waveguide (501) linearly varies from 4 μm to 5.652 μm, and the width of the output wedge waveguide (502) linearly varies from 5.652 μm to 4 μm.

[0030] As attached Figure 4 The image shows the transmission optical field of the 2×2 multimode interference coupler (300) described in this invention at a wavelength of 1550 nm. It can be observed that the beam splitting of the upper and lower channels is uniform at a wavelength of 1550 nm.

[0031] As attached Figure 5 The diagram shows a cross-sectional view of the 2×2 thermo-optic switch of the present invention. From bottom to top, the layers are a silicon substrate (1), a silicon dioxide lower cladding layer (2), a polymer waveguide core layer (3), a polymer upper cladding layer (4), and a metal electrode (5). In this example, a dense silicon dioxide layer (15 μm) with a refractive index of 1.4456 is grown on the silicon substrate (1) by thermal oxidation. The polymer waveguide core layer (3) is made of SU-8 2005 negative photoresist with a refractive index of 1.5802 at a wavelength of 1550 nm. The polymer upper cladding layer is made of polymethyl methacrylate (PMMA, 6 μm) with a refractive index of 1.47605 at a wavelength of 1550 nm. In this embodiment, in order to reduce crosstalk between modes and reduce manufacturing difficulty, the width and thickness of the first input waveguide (101), the second input waveguide (102), the first input S-bend waveguide (103), the second input S-bend waveguide (103'), the straight waveguide (109), the first modulation arm waveguide (104), the second modulation arm waveguide (105), the first output S-bend waveguide (106), the second output S-bend waveguide (106'), the first output waveguide (107), and the second output waveguide (108) are all designed to be 4μm×4μm.

[0032] As attached Figure 6 The image shown is a transmission optical field diagram of the 2×2 thermo-optical switch described in this invention. (Attached image) Figure 6 (a) is the light field diagram of the 2×2 thermo-optic switch of the present invention when no voltage is applied. When no voltage is applied, the output channels Output1 and Output2 are approximately equal in power. Figure 6 (b) is the optical field diagram when the 2×2 thermo-optical switch of the present invention applies a voltage to the first modulation arm waveguide (104) to generate a temperature change of 1.02564K. When a voltage is applied to the first modulation arm waveguide (104) to generate a temperature change of 1.02564K, the phase difference Δφ1 of the signal light before and after the voltage is applied in the first modulation arm waveguide (104) is -π / 2, and the light will only be output from the output channel Output2; Appendix Figure 6(c) is the optical field diagram when the 2×2 thermo-optical switch of the present invention applies a voltage to the second modulation arm waveguide (105) to generate a temperature change of 1.02564K. When a voltage is applied to the second modulation arm waveguide (105) to generate a temperature change of 1.02564K, the phase difference Δφ2 of the signal light before and after the voltage is applied in the second modulation arm waveguide (105) is -π / 2, and the light will only be output from the output channel Output1.

[0033] As attached Figure 7 The figure shows the simulation results of the switching characteristics of output channels Output1 and Output2 when the 2×2 thermo-optical switch of the present invention applies a voltage to the first modulation arm waveguide (104) to cause a temperature change of 1.02564K (the phase difference Δφ1 = -π / 2 of the signal light before and after the voltage is applied in the first modulation arm waveguide (104)). At this time, the simulated loss at a wavelength of 1550nm is -0.04776dB, and the extinction ratio is greater than 30dB.

[0034] As attached Figure 8 The figure shows the simulation results of the switching characteristics of output channels Output1 and Output2 when the 2×2 thermo-optical switch of the present invention applies a voltage to the second modulation arm waveguide (105) to cause a temperature change of 1.02564K (the phase difference Δφ2 = -π / 2 of the signal light before and after the voltage is applied in the second modulation arm waveguide (105)). At this time, the simulated loss at a wavelength of 1550nm is -0.05dB, and the extinction ratio is greater than 30dB.

[0035] Figure 7 and Figure 8 The results show that, with the presence of a phase shifter, the power consumption of the device described in this invention is reduced by half compared to traditional single-arm modulation.

[0036] Example 2

[0037] The fabrication steps of the 2×2 thermo-optical switch described in this invention are as follows: Figure 9 As shown:

[0038] Step 1: A silicon dioxide undercoat layer (2) with a thickness of 15 μm is grown on silicon substrate 1 by thermal oxidation. Before preparing the SU-8 2005 photoresist film, in order to improve the adhesion and uniformity of the SU-8 2005 photoresist film, the surface of the silicon dioxide undercoat layer (2) is treated by plasma process and then the sample is heated at 100°C for 3 minutes and then cooled.

[0039] Step 2: Use a vacuum spin coater to spin coat SU-8 2005 photoresist onto the silicon dioxide undercoat (2), set the spin speed to 8000 rpm and the spin coat time to 60 s, thereby forming a 4 μm thick SU-8 photoresist film (3); then bake it at 100°C for 3 min using a hot plate.

[0040] Step 3: Place the sample processed in Step 2 under a 365nm ultraviolet lithography machine for alignment and lithography, setting the optical power to 18mW / cm². 2 The exposure time is 4.5s. The structure and shape of the mask I used for exposure are the same as the structure and shape of the polymer core waveguide to be prepared. Then the sample is baked, that is, baked at 100℃ for 3min using a hot plate. Then it is immersed in SU-8 developer (PGMEA: Propyleneglygol-monomethylether-acetate) for 60s development, then rinsed in isopropanol for 10s to remove residual adhesive, and then the chip is dried by blower. During the development process, the chip is repeatedly briefly immersed in developer and isopropanol and dried until the pattern is completely developed. Then the chip is heated and baked with a hot plate at 120℃ for 30min to form SU-8 2005 mask layer (3). The pattern on mask I that is the same as the core waveguide structure to be prepared is transferred to SU-8 photoresist layer I. In order to be polarization insensitive, the width and height of the strip-shaped polymer core waveguide are the same, both of which are 4μm.

[0041] Step 4: Use a vacuum spin coater to spin coat the chip with PMMA in a 1:9 ratio of polymethyl methacrylate and cyclopentanone as the top coating. Set the spin coater speed to 2500 rpm and the spin coater time to 20 s to obtain the PMMA top coating (4). Use a hot plate to heat-cur the chip after spin coating PMMA at a temperature of 120℃ and a baking time of 30 min.

[0042] Step 5: Use an aluminum vapor deposition stage to deposit a 100nm thick aluminum film on the chip (5); use a vacuum spin coater to spin coat a 1.5μm thick positive photoresist BP212 on the chip (6) at a speed of 2500rpm for 60s; use a hot plate to heat and bake the chip at a temperature of 95℃ for 2min.

[0043] Step 6: Place the device processed in Step 5 under a 365nm ultraviolet lithography machine and perform photolithography by making it in close contact with mask II. The structure and shape of mask II are the same as those of the modulation electrode to be fabricated. The width of mask II is larger than that of the polymer core waveguide. Set the optical power to 18mW / cm. 2The exposure time is 3s; remove the modulation electrode mask II, immerse the chip in a 5‰ NaOH solution for a few seconds to develop and remove excess BP212, then use a hot plate to harden the film at a temperature of 95℃ for 10min. At this time, the pattern on mask II that is the same as the modulation electrode structure to be prepared has been transferred to the BP212 photoresist layer (6). Use a 5‰ NaOH solution again to remove the aluminum film that is not masked by the photoresist, and then blow dry the chip.

[0044] Step 7: Use a photolithography machine to perform a second exposure of the entire chip for 10 seconds to remove the remaining BP212, and then clean the chip with an ethanol solution until the aluminum electrode layer (5) is completely exposed. The aluminum modulation electrode is 20 μm wide and is located on the two modulation arms of MZI, thereby preparing the 2×2 thermo-optic switch of the present invention.

Claims

1. A dual-arm adjustable 2×2 thermo-optical switch with a phase shifter, characterized in that: From bottom to top, it consists of a silicon substrate (1), a silicon dioxide lower cladding (2), a polymer waveguide core layer (3), and a polymer upper cladding (4). The polymer waveguide core layer (3) and the polymer upper cladding (4) are located on the silicon dioxide lower cladding (2), and the polymer waveguide core layer (3) is completely covered by the polymer upper cladding (4). The polymer waveguide core layer (3) is an MZI type structure, consisting of a first input waveguide (101) and a second input waveguide (102) with the same structure and size and symmetrical, an input 2×2 multimode interference coupler (300), and a first input S-bend waveguide (103) and a second input S-bend waveguide (103') with the same structure and size and symmetrical. The system comprises a phase shifter (500), a straight waveguide (109), a first modulation arm waveguide (104) and a second modulation arm waveguide (105) of identical and symmetrical structure and size, a first output S-bend waveguide (106) and a second output S-bend waveguide (106') of identical and symmetrical structure and size, an output 2×2 multimode interference coupler (400), and a first output waveguide (107) and a second output waveguide (108) of identical and symmetrical structure and size; wherein, the first modulation arm waveguide (104) and the second modulation arm waveguide (105) are parallel to each other and are located on the polymer cladding (4) at the positions of the first modulation arm waveguide (104) and the second modulation arm waveguide (105). A first metal electrode (201) and a second metal electrode (202) are provided, which are parallel to each other; the first input waveguide (101) and the second input waveguide (102) serve as the first input channel (Input1) and the second input channel (Input2), respectively; the first output waveguide (107) and the second output waveguide (108) serve as the first output channel (Output1) and the second output channel (Output2), respectively; each S-bend waveguide is composed of two circular arcs of the same size and central symmetry, which are connected together to form an "S-bend" shape; the input 2×2 multimode interference coupler (300) and the output 2×2 multimode interference coupler (400) have the same structure. The input 2×2 multimode interference coupler (300) consists of a first input wedge waveguide (301) and a second input wedge waveguide (302) with the same structure and size and symmetrical, a first multimode interference region (303), a first output wedge waveguide (304) and a second output wedge waveguide (305) with the same structure and size and symmetrical; the output 2×2 multimode interference coupler (400) consists of a third input wedge waveguide (301') and a fourth input wedge waveguide (302') with the same structure and size and symmetrical, a second multimode interference region (303'), a third output wedge waveguide (304') and a fourth output wedge waveguide (305') with the same structure and size and symmetrical;The first input waveguide (101) and the first input wedge waveguide (301) are connected. The first output wedge waveguide (304) and the first input S-bend waveguide (103), phase shifter (500), first modulation arm waveguide (104), first output S-bend waveguide (106) and the third input wedge waveguide (301') are connected in sequence. The third output wedge waveguide (304') and the first output waveguide (107) are connected. The second input waveguide (102) and the second input wedge waveguide (301') are connected in sequence. 02) The second output wedge waveguide (305) and the second input S-bend waveguide (103'), straight waveguide (109), second modulation arm waveguide (105), second output S-bend waveguide (106') and fourth input wedge waveguide (302') are connected in sequence, and the fourth output wedge waveguide (305') and the second output waveguide (108) are connected; wherein, the refractive index of the silicon dioxide lower cladding (2) is 1.4456; the polymer waveguide core layer (3) is made of SU-8 2005 negative photoresist with a refractive index of 1.5802 at a wavelength of 1550nm; the polymer upper cladding (4) is made of polymethyl methacrylate with a refractive index of 1.47605 at a wavelength of 1550nm; the thickness of the silicon dioxide lower cladding (2) is 15μm; the thickness of the polymer upper cladding (4) is 6μm; The input light is input through the first input waveguide (101) or the second input waveguide (102), and then enters the input 2×2 multimode interference coupler (300) where it is split into two beams of equal power. One beam undergoes a π / 2 phase shift through the phase shifter (500), and the other beam passes through the straight waveguide (109) without phase shift before entering the first modulation arm waveguide (104) and the second modulation arm waveguide (105), respectively. The beams then pass through the first output S-bend waveguide (106) and the second output S-bend waveguide (106'), respectively, before entering the output 2×2 multimode interference coupler (400). When no voltage is applied to either modulation arm waveguide (i.e., there is no temperature difference between the two modulation arm waveguides), the light enters the output... The phase difference between the two beams of light in the 2×2 multimode interference coupler (400) is π / 2. The output light intensities of the first output channel (Output1) and the second output channel (Output2) are equal, both being half of the maximum light intensity. When light enters from the first input channel (Input1), if only the first metal electrode (201) is applied with voltage, and the phase difference Δφ1 of the signal light before and after applying voltage in the first modulation arm waveguide (104) is -π / 2, then the phase difference between the two beams of light entering the output 2×2 multimode interference coupler (400) is π / 2 + (-π / 2) = 0. The light is output from the second output channel (Output2), i.e., it is working in the Cross state, and the output light intensity is equal to the maximum light intensity. The input light intensity is the same; when only the second metal electrode (202) is applied with voltage, and the phase difference Δφ2=-π / 2 of the signal light before and after the voltage is applied in the second modulation arm waveguide (105), the phase difference of the two beams entering the output 2×2 multimode interference coupler (400) is π / 2-(-π / 2)=π, and the light is output from the first output channel (Output1), that is, it works in Bar state, and the output light intensity is the same as the input light intensity; when the light enters from the second input channel (Input2), when only the first metal electrode (201) is applied with voltage, and the phase difference Δφ1=-π / 2 of the signal light before and after the voltage is applied in the first modulation arm waveguide (104), the phase difference of the two beams entering the output 2×2 multimode interference coupler (400) is π / 2-(-π / 2)=π, and the light is output from the first output channel (Output1), that is, it works in Bar state, and the output light intensity is the same as the input light intensity; when the light enters from the second input channel (Input2), and only the first metal electrode (201) is applied with voltage, and the phase difference Δφ1=-π / 2 of the signal light before and after the voltage is applied in the first modulation arm waveguide (104), the phase difference of the two beams entering the output 2×2 multimode interference coupler (400) is π / 2-(-π / 2)=π, ... The phase difference between the two beams of light in the multimode interference coupler (400) is π / 2 + (-π / 2) = 0. The light is output from the first output channel (Output1), that is, it works in the Cross state, and the output light intensity is the same as the input light intensity. When only the second metal electrode (202) is applied, the phase difference Δφ2 = -π / 2 of the signal light before and after the voltage is applied in the second modulation arm waveguide (105) is π / 2 - (-π / 2) = π. The light is output from the first output channel (Output1), that is, it works in the Bar state, and the output light intensity is the same as the input light intensity. Thus, the dual-arm adjustable 2×2 thermo-optical switch function is realized.

2. The dual-arm adjustable 2×2 thermo-optical switch with a phase shifter as described in claim 1, characterized in that: The width and thickness of the first input waveguide (101), the second input waveguide (102), the first input S-bend waveguide (103), the second input S-bend waveguide (103'), the straight waveguide (109), the first modulation arm waveguide (104) and the second modulation arm waveguide (105), the first output S-bend waveguide (106), the second output S-bend waveguide (106'), the first output waveguide (107), and the second output waveguide (108) are 4μm×4μm, and the length of the first modulation arm waveguide (104) and the second modulation arm waveguide (105) is 2000μm.

3. A dual-arm adjustable 2×2 thermo-optical switch with a phase shifter as described in claim 1, characterized in that: The lengths of the first input wedge waveguide (301), second input wedge waveguide (302), first output wedge waveguide (304), second output wedge waveguide (305), third input wedge waveguide (301'), fourth input wedge waveguide (302'), third output wedge waveguide (304'), and fourth output wedge waveguide (305') are 13.5 μm. The widths of the first input wedge waveguide (301), second input wedge waveguide (302), third input wedge waveguide (301'), and fourth input wedge waveguide (302') change linearly from 4 μm to 5 μm. The first output wedge waveguide (304) and second output wedge waveguide (305') are... (305), the widths of the third output wedge waveguide (304') and the fourth output wedge waveguide (305') change linearly from 5 μm to 4 μm, the center spacing of the first input wedge waveguide (301) and the second input wedge waveguide (302), the first output wedge waveguide (304) and the second output wedge waveguide (305), the third input wedge waveguide (301') and the fourth input wedge waveguide (302'), the third output wedge waveguide (304') and the fourth output wedge waveguide (305') is 15 μm; the width of the first multimode interference region (303) and the second multimode interference region (303') is 20 μm and the length is 871 μm.

4. A dual-arm adjustable 2×2 thermo-optical switch with a phase shifter as described in claim 1, characterized in that: The phase shifter (500) consists of an input wedge waveguide (501) and an output wedge waveguide (502) from left to right. The length of the input wedge waveguide (501) and the output wedge waveguide (502) is 90 μm. The width of the input wedge waveguide (501) changes linearly from 4 μm to 5.652 μm, and the width of the output wedge waveguide (502) changes linearly from 5.652 μm to 4 μm.

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