Double-arm adjustable 2*2 thermo-optical switch with phase shifter

Abstract

The invention discloses a double-arm adjustable 2 * 2 thermo-optical switch with a phase shifter, and belongs to the technical field of optical communication. The invention discloses an MZI-type MZI-type polymer waveguide core layer which is composed of a silicon substrate, a silicon dioxide lower cladding layer, a polymer waveguide core layer and a polymer upper cladding layer, and the polymer waveguide core layer is of an MZI-type structure. The invention relates to an S-shaped waveguide dual-mode interferometer which is composed of two input waveguides, an input 2 * 2 multi-mode interference coupler, two input S-shaped bent waveguides, a phase shifter, a straight waveguide, a first modulation arm waveguide, a second modulation arm waveguide, two output S-shaped bent waveguides, an output 2 * 2 multi-mode interference coupler and two output waveguides. And two metal electrodes which are parallel to each other are arranged on the polymer upper cladding at the positions of the two modulation arm waveguides. The phase shifter introduces pi / 2 phase shift for the first modulation arm waveguide in advance, and the state change of the switch can be realized only by introducing the pi / 2 phase shift for each modulation arm waveguide, so that the double-arm adjustable 2 * 2 thermo-optical switch function is realized, and the effect of reducing the power consumption required by single modulation is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of optical communication, and in particular relates to a double-arm adjustable 2×2 thermo-optical switch with a phase shifter. Background Art

[0002] With the rapid development of information technology and the increasing demand for high-speed and high-bandwidth communications, optical communication has been widely used as a high-speed, large-capacity, and low-power communication method. In optical communication systems, optical switches are one of the core components used to realize the routing control of optical signals. At present, thermo-optical switches are widely used in optical communication systems as a common optical switch technology. Because they are suitable for large-scale production, integrated optical switch arrays have been widely studied. The working principle of most current thermo-optical switches is to modulate a single modulation arm so that the light passing through a single modulation arm produces a π phase change. As the number of interconnected ports increases, the simultaneous operation of the switches will generate extremely high power consumption, and will cause thermal crosstalk to the surrounding switches, and may even cause the array to fail. Therefore, in order to realize a low-power, large-scale optical switch array, a low-power thermo-optical switch is urgently needed. Summary of the invention

[0003] In order to solve the above problems existing in the prior art, the present 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 a phase shifter of the present 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, wherein 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); wherein the polymer waveguide core layer (3) is an MZI type structure, and comprises a first input waveguide (101) and a second input waveguide (102) having the same structure and size and being symmetrical, an input 2×2 multimode The invention comprises an 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 symmetry, a phase shifter (500), a straight waveguide (109), a first modulation arm waveguide (104) and a second modulation arm waveguide (105) of the same structure and size and symmetry, a first output S-bend waveguide (106) and a second output S-bend waveguide (106') of the same structure and size and symmetry, an output 2×2 multimode interference coupler (400), and a first output waveguide (107) and a second output waveguide (108) of the same structure and size and symmetry. 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) parallel to each other are arranged on a polymer upper cladding (4) at the positions where the first modulation arm waveguide (104) and the second modulation arm waveguide (105) are located. The first input waveguide (101) and the second input waveguide (102) serve as the first input channel (Input 1) and the second input channel (Input 2), respectively; the first output waveguide (107) and the second output waveguide (108) serve as the first output channel (Output 1) and the second output channel (Output 2), respectively; each S-bend waveguide is composed of two circular arcs of exactly the same size and central symmetry, 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) is composed of a first input wedge-shaped waveguide (301) and a second input wedge-shaped waveguide (302) having the same structure and size and being symmetrical, a first multimode interference region (303), and a first output wedge-shaped waveguide (304) and a second output wedge-shaped waveguide (305) having the same structure and size and being symmetrical; the output 2×2 multimode interference coupler (400) is composed of a third input wedge-shaped waveguide (301') and a fourth input wedge-shaped waveguide (302') having the same structure and size and being symmetrical, a second multimode interference region (303'), and a third output wedge-shaped waveguide (304') and a fourth output wedge-shaped waveguide (305') having the same structure and size and being symmetrical;

[0006] The first input waveguide (101) is connected to the first input wedge-shaped waveguide (301); the first output wedge-shaped 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-shaped waveguide (301') in sequence; the third output wedge-shaped waveguide (304') is connected to the first output waveguide (107); the second input waveguide (102) is connected to the second input wedge-shaped waveguide (302); the second output wedge-shaped 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-shaped waveguide (302') in sequence; and the fourth output wedge-shaped waveguide (305') is connected to the second output waveguide (108);

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

[0008] The input light is inputted from the first input waveguide (101) or the second input waveguide (102), and then enters the input 2×2 multimode interference coupler (300) and is divided into two beams of light with completely equal power. One of the two beams of light passes through a phase shifter (500) with a phase shift of π / 2, and the other 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, and then passes through the first output S-bend waveguide (106) and the second output S-bend waveguide (107) respectively. The polymer modulator arm waveguide (106') exits the S-bend waveguide (106') and enters the output 2×2 multimode interference coupler (400); when no voltage is applied to the first modulator arm waveguide (104) and the second modulator arm waveguide (105) (i.e., there is no temperature difference between the two modulator arm waveguides), the phase difference between the two beams of light entering the output 2×2 multimode interference coupler (400) is π / 2, and the output light intensity of the output channel (Output1) and the output channel (Output2) are equal, both of which are half of the maximum light intensity. When a voltage is applied to the metal electrode for modulation (i.e., the two modulator arm waveguides are heated), due to the thermo-optical effect, the refractive index of the polymer modulator arm waveguide changes with the increase in temperature, thereby causing the phase of the signal light in the polymer modulator arm waveguide to change when it arrives at 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), when voltage is applied only to the first metal electrode (201), since the thermo-optic coefficient of the polymer material is a negative number, the phase change caused by the voltage application is a negative number. When 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, the phase difference of 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), that is, the working When operating in the Cross state, the output light intensity is the same as the input light intensity; when voltage is applied only to the second metal electrode (202), and 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, 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 will be output from the output channel (Output 1), that is, it works in the Bar state, and the output light intensity is the same as the input light intensity, thereby realizing the function of two channel switches. When light enters from the input channel (Input2), when voltage is applied only to the first metal electrode (201), 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 phase difference of the two light beams 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), that is, it works in the Cross state, and the output light intensity is the same as the input light intensity; when voltage is applied only to the second metal electrode (202), 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 phase difference of the two light beams 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), that is, it works in the Bar state, and the output light intensity is the same as the input light intensity; thereby realizing the dual-arm adjustable 2×2 thermo-optical switch function.

[0009] When a modulation arm waveguide in the MZI structure is heated, the refractive index of the modulation arm waveguide changes, causing the phase of the light beam in the modulation arm waveguide to change, and then the two arm light beams are coupled and interfered to transform into a change in light amplitude; when the introduced phase shift reaches π, the switch state can be changed. In order to further reduce the power consumption required for the thermo-optical switch, the present invention introduces a π / 2 phase shifter (500) in the first modulation arm waveguide (104), and the phase shifter (500) is composed of an input wedge-shaped waveguide (501) and an output wedge-shaped waveguide (502). The main principle is to achieve the modulation of 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 for 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 achieve the state change of the switch, thereby changing the switch working state, which plays a role in reducing the power consumption required for a single modulation.

[0010] Compared with the prior art, the invention is innovative in that:

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

[0012] 2. Due to the introduction of the π / 2 phase shifter, each modulation only requires a π / 2 phase shift, which reduces the crosstalk of a single switch and facilitates large-scale integration;

[0013] 3. Due to the introduction of the π / 2 phase shifter, each modulation only requires a π / 2 phase shift, which reduces the refractive index change of a single modulation arm waveguide, thereby reducing the polarization-dependent loss caused by the refractive index change, which is conducive to large-scale integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 : Schematic diagram of the 2×2MZI thermo-optic switch polymer waveguide core layer and modulation electrode structure of the present invention;

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

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

[0018] Figure 4 : Light field transmission diagram of the 2×2 multimode interference coupler (300) of the present invention;

[0019] Figure 5 : Schematic diagram of the cross section of the 2×2 thermo-optical switch of the present invention;

[0020] Figure 6 : Transmission light field diagram of the 2×2 thermo-optic switch of the present invention, wherein (a) is a light field simulation diagram when no voltage is applied to any metal electrode; (b) is a light field simulation diagram when voltage is applied only to the first modulation arm waveguide (104) to cause the modulation arm waveguide to produce a temperature change of 1.02564K; (c) is a light field simulation diagram when voltage is applied only to the second modulation arm waveguide (105) to cause the modulation arm waveguide to produce a temperature change of 1.02564K;

[0021] Figure 7 : A diagram showing the switching characteristics simulation results of the output channel Output 1 and the output channel Output 2 when the 2×2 thermo-optic switch of the present invention applies a voltage to the first modulation arm waveguide (104) to cause the modulation arm waveguide to produce a temperature change of 1.02564K;

[0022] Figure 8 : A diagram showing the simulation results of the switching characteristics of the output channel Output1 and the output channel Output2 when the 2×2 thermo-optic switch of the present invention applies a voltage to the second modulation arm waveguide (105) to cause the modulation arm waveguide to produce a temperature change of 1.02564K;

[0023] Fig. 9 : Flow chart of the preparation process of the 2×2 thermo-optical switch described in the present invention. DETAILED DESCRIPTION

[0024] In order to further explain the core technical solution and application objectives of the present invention, the following is a description in conjunction with the accompanying drawings and embodiments. However, it should be noted that the scope of the present invention is not limited to the embodiments mentioned here.

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] As attached Figure 1 and Figure 5As shown, a dual-arm adjustable 2×2 thermo-optic switch with a phase shifter according to the present 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, wherein 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); wherein the polymer waveguide core layer (3) is an MZI type structure, comprising a first input waveguide (101) and a second input waveguide (102) having the same structure and size and being symmetrical, an input 2×2 multimode interference coupler (300), a first input S-bend waveguide (103) and a second input S-bend waveguide (103') having the same structure and size and being symmetrical, and a phase The invention is composed of a shifter (500), a straight waveguide (109), a first modulation arm waveguide (104) and a second modulation arm waveguide (105) having the same structure and size and being symmetrical, a first output S-bend waveguide (106) and a second output S-bend waveguide (106') having the same structure and size and being symmetrical, an output 2×2 multimode interference coupler (400), and a first output waveguide (107) and a second output waveguide (108) having the same structure and size and being 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 arranged on a polymer upper cladding (4) at the positions where the first modulation arm waveguide (104) and the second modulation arm waveguide (105) are located and are parallel to each other. The first input waveguide (101) and the second input waveguide (102) are used as the first input channel (input1) and the second input channel (input2), respectively; the first output waveguide (107) and the second output waveguide (108) are used as the first output channel (output1) and the second output channel (output2), respectively; each S-bend waveguide is composed of two circular arcs with completely identical sizes and central symmetry, which are connected together to form an "S-bend" shape; considering the relationship between modulation efficiency and size, the length of the first modulation arm waveguide (104) and the second modulation arm waveguide (105) is set to 2000 μm.

[0028] As attached Figure 2 (a) is a schematic diagram of the structure of the input 2×2 multimode interference coupler (300) of the present invention; Figure 2(b) is a schematic diagram of the structure of the output 2×2 multimode interference coupler (400) of the present invention; the input 2×2 multimode interference coupler (300) is composed of a first input wedge-shaped waveguide (301) and a second input wedge-shaped waveguide (302) with the same structure and size and symmetry, a first multimode interference region (303), a first output wedge-shaped waveguide (304) and a second output wedge-shaped waveguide (305) with the same structure and size and symmetry; the output 2×2 multimode interference coupler (400) is composed of a third input wedge-shaped waveguide (305) with the same structure and size and symmetry The invention relates to a first input wedge-shaped waveguide (301'), a fourth input wedge-shaped waveguide (302'), a second multimode interference region (303'), a third output wedge-shaped waveguide (304') and a fourth output wedge-shaped waveguide (305') having the same structure and size and being symmetrical; in this embodiment, considering the size of the device and the actual difficulty of preparation, the first input wedge-shaped waveguide (301), the second input wedge-shaped waveguide (302), the first output wedge-shaped waveguide (304), the second output wedge-shaped waveguide (305), the third input wedge-shaped waveguide (301'), the fourth input wedge-shaped waveguide (304'), the second output wedge-shaped waveguide (305') The lengths 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') 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') are linearly changed from 4 μm to 5 μm, and 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') are linearly changed from 4 μm to 5 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 as those of the output 2×2 multimode interference coupler (300).

[0029] As attached Figure 3 , which is a schematic diagram of the structure of the phase shifter (500) of the present invention. From left to right, there are an input wedge-shaped waveguide (501) and an output wedge-shaped waveguide (502). The lengths of the input wedge-shaped waveguide (501) and the output wedge-shaped waveguide (502) are both selected to be 90 μm, the width of the input wedge-shaped waveguide (501) changes linearly from 4 μm to 5.652 μm, and the width of the output wedge-shaped waveguide (502) changes linearly from 5.652 μm to 4 μm.

[0030] As attached Figure 4 , which is a transmission light field diagram of the 2×2 multimode interference coupler (300) of the present invention at a wavelength of 1550 nm. It can be found that at a wavelength of 1550 nm, the light splitting of the upper and lower channels is uniform.

[0031] As attached Figure 5 As shown, a schematic cross-sectional view of the 2×2 thermo-optic switch of the present invention. From bottom to top, there are silicon substrate (1), silicon dioxide lower cladding (2), polymer waveguide core layer (3), polymer upper cladding (4), and 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) material used is SU-8 2005 negative photoresist with a refractive index of 1.5802 at a wavelength of 1550 nm. The polymer upper cladding material used is 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 the crosstalk between modes and reduce the difficulty of process manufacturing, 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 designed to be 4μm×4μm.

[0032] As attached Figure 6 As shown in FIG. 1 , it is a transmission light field diagram of the 2×2 thermo-optic switch of the present invention. 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 channel Output1 and the output channel Output2 are approximately equal in power output; Figure 6 (b) is a light field diagram when the 2×2 thermo-optic 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 equal to -π / 2, and the light is output only from the output channel Output2; Figure 6(c) is a light 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 is output only from the output channel Output1.

[0033] As attached Figure 7 As shown, the switching characteristic simulation result diagram of the output channel Output1 and the output channel Output2 when the 2×2 thermo-optic switch of the present invention applies a voltage to the first modulation arm waveguide (104) to cause the modulation arm waveguide to produce 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). 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 As shown, the switching characteristics simulation result diagram of the output channel Output1 and the output channel Output2 when the 2×2 thermo-optic switch of the present invention applies a voltage to the second modulation arm waveguide (105) to cause the modulation arm waveguide to produce 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). 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, under the premise of the existence of a phase shifter, the power consumption of the device described in the present invention is reduced by half compared with the traditional single-arm modulation.

[0036] Example 2

[0037] The preparation steps of the 2×2 thermo-optical switch of the present invention are as follows: Fig. 9 As shown:

[0038] Step 1: growing a silicon dioxide lower cladding layer (2) with a thickness of 15 μm on a silicon substrate 1 by a thermal oxidation method; before preparing a SU-8 2005 photoresist film, in order to improve the adhesion and uniformity of the SU-8 2005 photoresist film, treating the surface of the silicon dioxide lower cladding layer (2) by a plasma process, and then heating the sample at 100° C. for 3 minutes on a hot plate and then cooling it down;

[0039] Step 2: Use a vacuum coating machine to spin-coat SU-8 2005 photoresist on the silicon dioxide lower cladding (2), set the rotation speed to 8000 rpm, and the coating time to 60 seconds, thereby forming a 4 μm thick SU-8 photoresist film (3); then use a hot plate to bake at 100° C. for 3 minutes;

[0040] Step 3: Place the sample processed in step 2 under a 365nm UV photolithography machine for plate alignment, and set the light power to 18mW / cm 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 post-baked, that is, baked at 100°C for 3min using a hot plate; then it is immersed in SU-8 developer (PGMEA: Propyleneglygol-monomethylether-acetate) for 60s of development, and then rinsed in isopropanol for 10s to remove the residual glue, and then the chip is blown dry with an ear cleaner. During the development process, the chip is repeatedly immersed in the developer and isopropanol for a short time and blown dry until the pattern is completely developed; then the chip is heated and baked on a hot plate at a temperature of 120°C for 30min to form a SU-8 2005 mask layer (3), and the pattern on the mask I with the same structure as the core waveguide to be prepared is transferred to the SU-8 photoresist layer I. In order to be polarization-insensitive, the width and height of the polymer core waveguide with a strip structure are the same, both of which are 4μm;

[0041] Step 4: Use a vacuum coating machine to spin-coat PMMA (polymethyl methacrylate:cyclopentanone in a ratio of 1:9) on the chip as an upper cladding layer, set the spin coating speed to 2500 rpm, and the spin coating time to 20 s, to obtain a PMMA upper cladding layer (4); use a hot plate to heat cure the chip after spin coating with PMMA, the temperature is 120° C., and the baking time is 30 min;

[0042] Step 5: Use an aluminum vapor deposition table to deposit a 100 nm thick aluminum film (5) on the chip; Use a vacuum coating machine to spin coat a 1.5 μm thick positive photoresist BP212 (6) on the chip at a rotation speed of 2500 rpm for 60 seconds; Use a hot plate to heat and bake the chip at a temperature of 95° C. for 2 minutes;

[0043] Step 6: Place the device processed in step 5 under a 365nm UV photolithography machine and place it in close contact with mask II for alignment photolithography. The structure and shape of the mask II used are the same as those of the modulation electrode to be prepared. The width of mask II is larger than that of the polymer core waveguide. Set the optical power to 18mW / cm 2, the exposure time is 3s; remove the modulation electrode mask II, immerse the chip in a 5‰ mass concentration NaOH solution for a few seconds to develop to remove excess BP212, and then use a hot plate to harden the film, the heating temperature is 95°C, the time is 10min, at this time, the pattern on the mask II that is the same as the modulation electrode structure to be prepared has been transferred to the BP212 photoresist layer (6), and use a 5‰ mass concentration 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 has a width of 20 μm and is located on the two modulation arms of the MZI, thereby preparing the 2×2 thermo-optical switch of the present invention.

Claims

1. A dual-arm adjustable 2×2 thermo-optic switch with a phase shifter, characterized in that: The 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, wherein 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); wherein the polymer waveguide core layer (3) is an MZI type structure, and comprises a first input waveguide (101) and a second input waveguide (102) of the same structure and size and symmetry, 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 symmetry. , a phase shifter (500), a straight waveguide (109), a first modulation arm waveguide (104) and a second modulation arm waveguide (105) having the same structure and size and being symmetrical, a first output S-bend waveguide (106) and a second output S-bend waveguide (106') having the same structure and size and being symmetrical, an output 2×2 multimode interference coupler (400), and a first output waveguide (107) and a second output waveguide (108) having the same structure and size and being symmetrical; wherein the first modulation arm waveguide (104) and the second modulation arm waveguide (105) are parallel to each other, and on the polymer upper cladding (4) where the first modulation arm waveguide (104) and the second modulation arm waveguide (105) are located 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) are used as a first input channel (Input 1) and a second input channel (Input 2) respectively, and the first output waveguide (107) and the second output waveguide (108) are used as a first output channel (Output 1) and a second output channel (Output 2) respectively; each S-bend waveguide is composed of two circular arcs of completely identical 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) is composed of a first input wedge-shaped waveguide (301) and a second input wedge-shaped waveguide (302) having the same structure and size and being symmetrical, a first multimode interference region (303), and a first output wedge-shaped waveguide (304) and a second output wedge-shaped waveguide (305) having the same structure and size and being symmetrical; the output 2×2 multimode interference coupler (400) is composed of a third input wedge-shaped waveguide (301') and a fourth input wedge-shaped waveguide (302') having the same structure and size and being symmetrical, a second multimode interference region (303'), and a third output wedge-shaped waveguide (304') and a fourth output wedge-shaped waveguide (305') having the same structure and size and being symmetrical;The first input waveguide (101) is connected to the first input wedge-shaped waveguide (301); the first output wedge-shaped 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-shaped waveguide (301') in sequence; the third output wedge-shaped waveguide (304') is connected to the first output waveguide (107); the second input waveguide (102) is connected to the second input wedge-shaped waveguide (302); the second output wedge-shaped 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-shaped waveguide (302') in sequence; and the fourth output wedge-shaped waveguide (305') is connected to the second output waveguide (108).

2. A dual-arm adjustable 2×2 thermo-optic switch with a phase shifter as claimed in claim 1, characterized in that: The thickness of the silica lower cladding (2) is 15 μm, and the refractive index is 1.4456; the material of the polymer waveguide core layer (3) is SU-8 2005 negative photoresist, with a refractive index of 1.5802 at a wavelength of 1550nm; the polymer upper coating material is polymethyl methacrylate, with a thickness of 6μm and a refractive index of 1.47605 at a wavelength of 1550nm; 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-optic switch with a phase shifter as claimed in claim 1, characterized in that: The lengths 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') 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 first output wedge waveguide (304), the second 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 width of the first multimode interference region (303) and the second multimode interference region (303') varies linearly from 20 μm to 4 μm. The center spacing between the first input wedge-shaped waveguide (301) and the second input wedge-shaped waveguide (302), the first output wedge-shaped waveguide (304) and the second output wedge-shaped waveguide (305), the third input wedge-shaped waveguide (301') and the fourth input wedge-shaped waveguide (302'), the third output wedge-shaped waveguide (304') and the fourth output wedge-shaped 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-optic switch with a phase shifter as claimed in claim 1, characterized in that: The phase shifter (500) consists of an input wedge-shaped waveguide (501) and an output wedge-shaped waveguide (502) from left to right. The lengths of the input wedge-shaped waveguide (501) and the output wedge-shaped waveguide (502) are 90 μm, the width of the input wedge-shaped waveguide (501) changes linearly from 4 μm to 5.652 μm, and the width of the output wedge-shaped waveguide (502) changes linearly from 5.652 μm to 4 μm.

5. A dual-arm adjustable 2×2 thermo-optic switch with a phase shifter as claimed in claim 1, characterized in that: Input light is input from a first input waveguide (101) or a second input waveguide (102), and then enters an input 2×2 multimode interference coupler (300) and is divided into two beams of light with completely equal power. One of the two beams of light passes through a phase shifter (500) to generate a phase shift of π / 2, and the other beam of light passes through a straight waveguide (109) without phase shift and then enters a first modulation arm waveguide (104) and a second modulation arm waveguide (105) respectively, and then passes through a first output S-bend waveguide (106) and a second output S-bend waveguide (106') respectively to enter an output 2×2 multimode interference coupler (400). When no voltage is applied to the two modulation arm waveguides (i.e., there is no temperature difference between the two modulation arm waveguides), at this time The phase difference between the two beams of light entering the output 2×2 multimode interference coupler (400) is π / 2, and the output light intensities of the output channel (Output 1) and the output channel (Output 2) are equal, both being half of the maximum light intensity; when light enters from the input channel (Input 1), when voltage is applied only to the first metal electrode (201), and 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, 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 (Output 2), that is, it works in the Cross state, and the output light intensity is equal to The input light intensity is the same; when a voltage is applied only to the second metal electrode (202), the phase difference of the signal light before and after the voltage is applied in the second modulation arm waveguide (105) is Δφ2=-π / 2, and the phase difference of the two light beams entering the output 2×2 multimode interference coupler (400) is π / 2-(-π / 2)=π, and the light is output from the output channel (Output1), that is, it works in the Bar state, and the output light intensity is the same as the input light intensity; when the light enters from the input channel (Input2), when a voltage is applied only to the first metal electrode (201), the phase difference of the signal light before and after the voltage is applied in the first modulation arm waveguide (104) is Δφ1=-π / 2, and the light enters the output 2×2 The phase difference between the two beams of light in the multimode interference coupler (400) is π / 2+(-π / 2)=0, and the light is output from the output channel (Output 1), that is, it works in the Cross state, and the output light intensity is the same as the input light intensity; when voltage is applied only to the second metal electrode (202), and 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, 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 (Output 1), that is, it works in the Bar state, and the output light intensity is the same as the input light intensity; thereby realizing the dual-arm adjustable 2×2 thermo-optical switch function.

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