A 1×3 optical switch with multi-mode switching based on phase change material and its preparation method

Abstract

The present invention relates to a 1×3 optical switch for multi-mode switching based on phase change materials and a preparation method thereof. The optical switch structure is to arrange three straight strip Si waveguides and two straight strip composite waveguides in parallel on a substrate to form a single straight waveguide region, an uplink coupling waveguide region and a downlink coupling waveguide region; according to the designed waveguide structure, a focused electron beam exposure process is first used to obtain five Si waveguides, and then the Si waveguide of the composite waveguide is magnetron sputtered to deposit a multi-component sulfide phase change film switch unit on the Si waveguide of the composite waveguide. The present invention is controlled by a phase change material film covering the composite waveguide in the optical switch coupling region. By switching the phase state of the phase change film, the input electromagnetic field fundamental mode can be three-way gated and mode switched by three strip Si waveguides for the fundamental mode, first-order mode and second-order mode, respectively, to realize the optical switch switching function of mode separation and multiplexing, and has the characteristics of mode gated, high integration, small size and high switching rate.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronic technology, and particularly relates to a 1×3 optical switch for multi-mode switching based on phase change materials and a preparation method thereof. Background Art

[0002] With the development of technology in the fields of virtual reality, big data and artificial intelligence, higher and higher requirements are put forward for the capacity of communication. Improving the transmission capacity of optical communication, reducing losses, improving integration density and regulation efficiency are all key issues that need to be solved in the further development of optical communication and silicon-based optical switch technology. In short data center networks, network reconstruction is usually required according to dynamic needs, and the current reconfiguration is mainly completed by high-speed electrical switching switches, that is, the input signal is converted into an electrical signal, and then converted back to an optical signal after the exchange is completed in the electrical domain. This optical / electrical / optical (O / E / O) conversion usually requires a receiver and a transmitter, and each optical path must pass through a multiplexer, a demultiplexer and multiple O / E / O conversions, which increases the complexity of the data link reconstruction of the switching node and has high power consumption and high hardware cost. Silicon-based optical waveguide switches are a recognized low-cost optical switching technology with very broad application prospects in fields such as telecommunication networks and data centers. Optical switches are the core units used for data exchange in optical switching networks. They can realize the switching of data and signals in multi-mode channels. They are an indispensable part of building a more flexible and effective mode division multiplexing network and realizing the functions of silicon chip all-optical networks.

[0003] At present, the research on silicon-based optical waveguide switches is mainly focused on Mach-Zehnder interferometer optical waveguide switches based on the principle of optical interference (see reference: Lin Y, Zhou T, Hao J, et al. General architecturesfor on-chip optical space and mode switching[J]. Optica, 2018, 5(2):180.), microring resonator optical waveguide switches (see reference: Nikolova D, Calhoun DM, Liu Y, Rumley S, et.Al. Modular architecture for fully non-blocking silicon photonic switchfabric Microsystems & Nanoengineering 3 1-9 16071,2017) and micro-electromechanical system (MEMS) driven waveguide optical switches (see reference: TJ Seok, N. Quack, S. Han, et. Al., Large-scalebroadband digital silicon photonic switches with vertical adiabatic couplers,Optica, vol. 3, no. 1, pp. 64, Jan. 2016). The phase shifter in the Mach-Zehnder or microring resonator silicon-based optical waveguide switch is made of silicon-doped PN junction material; the phase difference is formed by applying a voltage to the phase-shift interference arm through electro-optical modulation, which causes the refractive index change. Since the refractive index change of silicon material is very small (generally: ∆n<0.01), the length of the optical interference arm and the size of the waveguide structure reach hundreds of microns, making the size of the entire unit switch structure larger; and the switch state requires continuous voltage maintenance, making the device volatile. MEMS optical waveguide switch is a new type of wavelength selective switch with low crosstalk, but its disadvantages are that its movable parts have a large mass, a slow response time (about 300 microseconds), and a very high driving voltage.

[0004] The use of phase change material films in phase shift units of optical waveguide switches to replace interference arms and make reconfigurable mode multiplexing optical waveguide switch unit devices has gradually emerged. Phase change materials are covered on silicon-based strip waveguides to form composite waveguides, and the huge refractive index difference between the crystalline and amorphous states and before and after the phase change is used to change the propagation path of the optical signal. At present, the structure of a 1×3 optical waveguide switch that uses phase change material films combined with silicon can be found (see the literature: He, Jie, Junbo Yang, Hansi Ma, et al. Design of a Multi-FunctionalIntegrated Optical Switch Based on Phase Change Materials, Photonics 2022, 9(320):1-13.), this structure contains three long waveguides, two of which are curved waveguides. Curved waveguides are prone to greater optical loss and crosstalk, and increase the experimental difficulty of the device, thus limiting the greater multiplexing and integration of such optical switches. This technology needs to be further developed and utilized. Summary of the invention

[0005] In view of the deficiencies in the existing prior art, the present invention provides a multi-mode switching 1×3 type optical waveguide switch based on phase change material, which has high extinction ratio, small size, fast switching rate, single-input-three-output multi-channel selection input, gating and arbitrary mode switching functions, and a preparation method thereof.

[0006] The technical solution to achieve the purpose of the present invention is to provide a method for preparing a multi-mode switching 1×3 type optical switch based on a chalcogenide phase change material, comprising the following steps:

[0007] (1) Design of waveguide structure

[0008] The middle Si straight waveguide is arranged in the middle of the optical switch, one side is arranged as an uplink coupling waveguide area, including an uplink Si straight waveguide and an uplink composite waveguide, and the other side is arranged as a downlink coupling waveguide area composed of a downlink composite waveguide and a downlink Si straight waveguide; the waveguides are parallel to each other, with a spacing of 100 to 200 nanometers, the Si straight waveguides and the composite waveguides are alternately distributed, the uplink composite waveguide is located in the front end area of ​​the middle Si straight waveguide, and the downlink composite waveguide is located in the back end area of ​​the middle Si straight waveguide; the optical input port and the fundamental mode output port of the light wave are arranged at the front and back ends of the middle Si straight waveguide respectively; the first-order mode output port of the light wave is arranged at the back end of the uplink Si straight waveguide; the second-order mode output port of the light wave is arranged at the back end of the downlink Si straight waveguide; the uplink composite waveguide and the downlink composite waveguide are formed by depositing a layer of phase change material film on the Si waveguide;

[0009] (2) Preparation of waveguide structure

[0010] In SiO 2 The substrate material is covered with photoresist, and a focused electron beam exposure process is used to prepare a Si waveguide having three Si straight waveguides and two composite waveguides on the substrate according to the waveguide structure designed in step (1);

[0011] (3) Integration of phase change materials

[0012] The waveguide structure obtained in step (2) is subjected to photoresist spin coating, and the Si waveguide of the composite waveguide is subjected to electron beam exposure, and then a multi-component sulfide phase change film with a thickness of 10 to 300 nanometers is deposited on the Si waveguide of the composite waveguide by a magnetron sputtering process; the magnetron sputtering process parameters include: an Ar gas flow rate of 50 sccm, a sulfide target sputtering power of 20 to 50 W, a sputtering pressure of 0.8 to 1.2 Pa, and a sputtering time of 2 to 10 minutes; the sulfide target is any two or more of Ge, Sb, Se and Te elements;

[0013] (4) The photoresist is stripped off to obtain a multi-mode switching 1×3 optical switch based on chalcogenide phase change material.

[0014] In the technical solution of the present invention, the thickness of the substrate is 1 micron to 100 microns; in the waveguide structure, the distance between each waveguide is 100 to 200 nanometers; the thickness of the midline Si straight waveguide, the uplink Si straight waveguide and the downlink Si straight waveguide is 100 to 400 nanometers, the width is 200 to 600 nanometers, 600 to 1100 nanometers and 1100 to 1900 nanometers, and the length is 10 to 80 micrometers, 20 to 80 micrometers and 10 to 30 micrometers, respectively; the width of the uplink composite waveguide and the downlink composite waveguide is 200 to 600 nanometers, the length is 5 to 30 micrometers, the thickness of their Si waveguides is 100 to 400 nanometers, and the thickness of the phase change material film layer is 10 to 100 nanometers.

[0015] The technical solution of the present invention also includes a multi-mode switching 1×3 type optical waveguide switch based on phase change material obtained according to the above preparation method.

[0016] In the technical solution of the present invention, the optical switch utilizes the phase change characteristics of the sulfide phase change film to achieve the selective output of three paths of the light wave mode, so that the fundamental mode, first-order mode and second-order mode of the transverse electric mode (TE) or transverse magnetic mode (TM) can be switched arbitrarily. The effective refractive index of the mode in the waveguide is closely related to the size of the waveguide. The effective refractive index of the fundamental mode and the higher-order mode gradually increases with the increase of the waveguide width. When the effective refractive index is the same, the larger the waveguide width needs to be to accommodate the higher-order mode. The size of the strip waveguide is determined by the dispersion curve of the polarization mode.

[0017] The 1×3 optical switch provided by the present invention has two three-waveguide directional couplers, both of which contain three supermodes A, B and C. When the waveguide size is determined, the coupling spacing and the optimal coupling length can be determined based on the principle that the mode transmission meets the three-waveguide phase matching condition, that is, the effective refractive index of the three supermodes must meet the following conditions:

[0018]

[0019] Where N A , N B and N C They are the effective refractive indices of the three supermodes A, B and C respectively.

[0020] The optimal coupling length of the three waveguides meets the following conditions:

[0021]

[0022] Where Lc is the coupling length, λ is the operating wavelength.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention etches and deposits the strip Si waveguide and the chalcogenide phase change film on the SiO 2 A single-input and three-output fully straight waveguide optical switch is formed on the substrate. The waveguide switch has a mode selection function. The strip straight waveguide structure greatly reduces the experimental difficulty and improves efficiency. It has the characteristics of high extinction ratio, small size, and fast switching rate.

[0025] 2. The present invention can achieve the functions of single-input-three-output multi-channel selection input, gating and arbitrary mode switching by changing the phase state of the phase change material on the composite strip waveguide. When the phase change film in the upstream composite waveguide or the downstream composite waveguide is amorphous with low emissivity and low loss, and meets the optimal coupling length, the light wave mode will be output in the form of a first-order mode in the upstream Si straight waveguide, or in the form of a second-order mode in the downstream Si straight waveguide; when the phase change films in both composite straight waveguides are crystalline with high refractive index, the input fundamental mode light wave will be transmitted along the straight waveguide of the input port to the output port. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 , 2 They are respectively a schematic top view and a side stereoscopic view of the structure of a multi-mode switching 1×3 type optical waveguide switch based on phase change material provided by an embodiment of the present invention;

[0027] In the figure, 1. single straight waveguide region; 2. uplink coupled waveguide region; 3. downlink coupled waveguide region; 4. uplink Si straight waveguide; 5. uplink composite waveguide; 6. midlink Si straight waveguide; 7. downlink composite waveguide; 8. downlink Si straight waveguide; 9. silicon dioxide substrate; 10. Si waveguide in the composite waveguide; 11. phase change material film in the composite waveguide; 12. light input port; 13. fundamental mode output port of light wave; 14. first-order mode output port of light wave, or uplink output port; 15. second-order mode output port of light wave, or downlink output port.

[0028] Figure 3 The present invention provides a dispersion curve and a light wave mode field distribution diagram of the effective refractive index of the light wave mode in the multi-mode switching 1×3 type optical waveguide switch structure based on phase change material, which varies with the waveguide width.

[0029] Figure 4 This is a light intensity distribution diagram of a multi-mode switching 1×3 type optical waveguide switch structure based on phase change material provided by an embodiment of the present invention when the TE mode is input from the light input port 12 and output from the fundamental mode output port 13 of the light wave.

[0030] Figure 5 This is a light intensity distribution diagram of a multi-mode switching 1×3 type optical waveguide switch structure based on phase change material provided by an embodiment of the present invention when the TE mode is input from the optical input port 12 and output from the first-order mode output port 14 of the uplink coupling waveguide region.

[0031] Figure 6 This is a light intensity distribution diagram of a multi-mode switching 1×3 type optical waveguide switch structure based on phase change material provided by an embodiment of the present invention when the TE mode is input from the optical input port 12 and output from the second-order mode output port 15 of the downstream coupling waveguide region.

[0032] Figure 7 It is an extinction ratio and insertion loss curve when the TE mode is input from the optical input port 12 and output from the fundamental mode output port 13 in the multi-mode switching 1×3 type optical waveguide switch structure based on phase change material provided by an embodiment of the present invention.

[0033] Figure 8 It is an extinction ratio and insertion loss curve when the TE mode is input from the optical input port 12 and output from the first-order mode output port 14 of the uplink coupling waveguide region in the multi-mode switching 1×3 type optical waveguide switch structure based on phase change material provided by an embodiment of the present invention.

[0034] Fig. 9 It is an extinction ratio and insertion loss curve when the TE mode is input from the optical input port 12 and output from the second-order mode output port 15 of the downstream coupling waveguide region in the multi-mode switching 1×3 type optical waveguide switch structure based on phase change material provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0036] Example 1

[0037] The present invention provides a multi-mode switching 1×3 type optical waveguide switch based on phase change material and a preparation method thereof. The optical waveguide switch is composed of five parallel strip straight waveguides, three of which are Si waveguides and two are waveguides composited with phase change material film and Si, forming a single straight waveguide region and two coupled waveguide regions. The steps of the preparation method of the optical waveguide switch are as follows:

[0038] (1) Design of waveguide structure

[0039] See attached Figure 1 , 2 , are respectively a top view schematic diagram and a three-dimensional schematic diagram of the 1×3 optical waveguide switch structure provided in this embodiment; Si waveguides and composite waveguides are arranged on a silicon dioxide substrate 9, and the specific structure is as follows: a single straight waveguide region 1 composed of a middle Si straight waveguide 6 is arranged in the middle of the optical switch, one side is an uplink coupled waveguide region 2 composed of an uplink Si straight waveguide 4 and an uplink composite waveguide 5, and the other side is a downlink coupled waveguide region 3 composed of a downlink composite waveguide 7 and a downlink Si straight waveguide 8. The waveguides are parallel to each other, with a spacing of 100 to 200 nanometers, and the Si straight waveguides and composite waveguides are alternately distributed, the uplink composite waveguide 5 is located in the front end region of the middle Si straight waveguide 6, and the downlink composite waveguide 7 is located in the rear end region of the middle Si straight waveguide 6. The optical input port 12 and the fundamental mode output port 13 of the light wave are respectively located at the front and rear ends of the mid-line Si straight waveguide 6; the first-order mode output port 14 of the light wave is located at the rear end of the upstream Si straight waveguide 4; and the second-order mode output port 15 of the light wave is located at the rear end of the downstream Si straight waveguide 8.

[0040] Depend on Figure 2 It can be seen that the uplink composite waveguide 5 and the downlink composite waveguide 7 are formed by depositing or covering a layer of phase change material film 11 on the Si waveguide 10 .

[0041] (2) Preparation of waveguide structure

[0042] In SiO 2 The substrate material (thickness of 1 μm to 100 μm) is covered with photoresist, and a focused electron beam exposure process is used to prepare a Si waveguide 10 having three Si straight waveguides and two composite waveguides on the substrate according to the waveguide structure designed in step (1);

[0043] (3) Integration of phase change materials

[0044] The waveguide structure obtained in step (2) is subjected to photoresist spin coating, and the Si waveguide 10 of the composite waveguide is subjected to electron beam exposure, and then a multi-component sulfide phase change film 11 with a thickness of 10 to 300 nanometers is deposited on the Si waveguide 10 of the composite waveguide by a magnetron sputtering process; the magnetron sputtering process parameters include: an Ar gas flow rate of 50 sccm, a sulfide target sputtering power of 20 to 50 W, a sputtering pressure of 0.8 to 1.2 Pa, and a sputtering time of 2 to 10 minutes; the sulfide target is any two or more of Ge, Sb, Se and Te elements;

[0045] (4) The photoresist is stripped off to obtain a multi-mode switching 1×3 optical switch based on chalcogenide phase change material.

[0046] The 1×3 optical waveguide switch provided by the present invention has a thickness of 100-400 nanometers for the upstream Si straight waveguide 6, the upstream Si straight waveguide 4 and the downstream Si straight waveguide 8, respectively, and a width of 200-600 nanometers, 600-1100 nanometers and 1100-1900 nanometers, respectively, and a length of 10-80 micrometers, 20-80 micrometers and 10-30 micrometers, respectively. The width of the upstream composite waveguide 5 and the downstream composite waveguide 7 is 200-600 nanometers, and the length is 5-30 micrometers; the thickness of their Si waveguide 10 is 100-400 nanometers, and the thickness of the phase change material film 11 is 10-100 nanometers.

[0047] The 1×3 optical waveguide switch structure provided in this embodiment can change the output mode of the optical signal and select the output port according to the phase state of the phase change material film of the composite waveguide in the upstream or downstream area.

[0048] In this embodiment, the thickness of the three Si straight waveguides and the Si straight waveguides in the two composite waveguides is 300 nanometers; the widths of the middle Si straight waveguide 6, the uplink Si straight waveguide 4 and the downlink Si straight waveguide 8 are 400 nanometers, 832 nanometers and 1263 nanometers respectively; the widths of the two composite waveguides are 370 nanometers, the thickness of the sulfide phase change material layer is 65 nanometers, the length of the uplink composite waveguide 5 is 20.5 micrometers, and the length of the downlink composite waveguide 7 is 21.5 micrometers; the spacing between the five straight waveguides is 150 nanometers. The width of the entire device is 3.5 micrometers and the length is 50 micrometers.

[0049] In this embodiment, the magnetron sputtering target material is composed of a quaternary material of Ge-Sb-Se-Te with an element ratio of 2:2:4:1. The refractive indices after sputtering film formation are 5.03+0.4i (crystalline) and 2.86+0.003i (amorphous).

[0050] See attached Figure 3, is the dispersion curve and optical mode field distribution diagram of the effective refractive index of the optical wave mode in the 1×3 optical waveguide switch structure based on multi-mode switching provided by this embodiment, which varies with the waveguide width. In the figure, curves 1, 2 and 3 are respectively the dispersion curves of the zero-order fundamental mode, the first-order mode and the second-order mode excited in the waveguide when the transverse electric mode TE light wave is input. When the supermode effective refractive index matching is satisfied, the larger the size of the waveguide, the more modes can be excited. By Figure 3 It can be seen that at the communication band of 1550 nanometers, when the effective refractive index is 2.466, the width of the Si waveguide corresponding to the fundamental mode is 400 nanometers, the width corresponding to the first-order mode is 832 nanometers, and the width corresponding to the second-order mode is 1263 nanometers. Figure 3 Figures a, b, and c in the figure correspond to the mode field distribution diagrams of the zero-order fundamental mode, the first-order mode, and the second-order mode, that is, the energy distribution diagrams.

[0051] See also Figure 4 , is a light intensity distribution diagram of the 1×3 optical waveguide switch structure based on multi-mode switching provided by this embodiment when the TE mode is input from the optical input port 12 and the fundamental mode output port 13 of the light wave is output. At this time, the phase change materials in the upstream composite waveguide 5 and the downstream composite waveguide 7 are both in a crystalline state, and the fundamental mode output port 13 of the light wave outputs the zero-order fundamental mode.

[0052] See also Figure 5 , is a light intensity distribution diagram of the 1×3 optical waveguide switch structure based on multi-mode switching provided by this embodiment when the TE mode is input from the optical input port 12 and output from the upstream output port 14. At this time, the phase change material in the upstream composite waveguide 5 is amorphous, the phase change material in the downstream composite waveguide 7 is crystalline, the upstream coupling waveguide region 2 meets the supermode coupling condition, and the output of the upstream output port 14 is the first-order mode.

[0053] See also Figure 6 , is a light intensity distribution diagram of the 1×3 optical waveguide switch structure based on multi-mode switching provided by this embodiment when the TE mode is input from the optical input port 12 and output from the downstream port 15. At this time, the phase change material in the upstream composite waveguide 5 is crystalline, the phase change material in the downstream composite waveguide 7 is amorphous, the downstream coupling waveguide region 3 meets the supermode coupling condition, and the downstream output port 15 outputs the second-order mode.

[0054] See attached Figure 7 , is the extinction ratio and insertion loss curve when the TE mode is input from the optical input port 12 and output from the fundamental mode output port 13 of the light wave in the 1×3 optical waveguide switch structure based on multi-mode switching provided by this embodiment. Curve 1 is the extinction ratio, and curve 2 is the insertion loss. At this time, the phase change materials in the upstream composite waveguide 5 and the downstream composite waveguide 7 are both crystalline, and the corresponding output ports are the zero-order fundamental mode; at the optical communication band of 1550 nanometers, the extinction ratio and insertion loss of the optical switch are 16.19 dB and 1.19 dB respectively.

[0055] See attached Figure 8 , is the extinction ratio and insertion loss curve when the TE mode is input from the optical input port 12 and output from the upstream output port 14 in the 1×3 optical waveguide switch structure based on multi-mode switching provided by this embodiment. Curve 1 is the extinction ratio, and curve 2 is the insertion loss. At this time, the phase change material in the upstream composite waveguide 5 is amorphous, the phase change material in the downstream composite waveguide 7 is crystalline, the upstream coupling waveguide region 2 meets the supermode coupling condition, and the output port of the upstream output port 14 is the first-order mode; at the optical communication band of 1550 nanometers, the extinction ratio and insertion loss of the optical switch are 17.2dB and 0.148dB respectively.

[0056] See attached Fig. 9 , is the extinction ratio and insertion loss curve when the TE mode is input from the optical input port 12 and output from the downstream port 15 in the 1×3 optical waveguide switch structure based on multi-mode switching provided by this embodiment. Curve 1 is the extinction ratio, and curve 2 is the insertion loss. At this time, the phase change material in the upstream composite waveguide 5 is crystalline, the phase change material in the downstream composite waveguide 7 is amorphous, the downstream coupling waveguide region 3 meets the supermode coupling condition, and the output of the downstream output port 15 is the second-order mode; at the optical communication band of 1550 nanometers, the extinction ratio and insertion loss of the optical switch are 16.19 dB and 0.71 dB respectively.

Claims

1. A method for preparing a multi-mode switching 1×3 optical switch based on chalcogenide phase change materials, characterized in that The steps include: (1) Design of waveguide structure The middle Si straight waveguide (6) is arranged in the middle of the optical switch, one side is arranged as an uplink coupling waveguide region (2), including an uplink Si straight waveguide (4) and an uplink composite waveguide (5), and the other side is arranged as a downlink coupling waveguide region (3) composed of a downlink composite waveguide (7) and a downlink Si straight waveguide (8); the waveguides are parallel to each other, with a spacing of 100 to 200 nanometers, the Si straight waveguides and the composite waveguides are alternately distributed, the uplink composite waveguide (5) is located at the front end region of the middle Si straight waveguide (6), and the downlink composite waveguide (7) is located at the back end region of the middle Si straight waveguide (6); the optical input port (12) and the fundamental mode output port (13) of the optical wave are arranged at the front and back ends of the middle Si straight waveguide (6), respectively; the first-order mode output port (14) of the optical wave is arranged at the back end of the uplink Si straight waveguide (4); and the second-order mode output port (15) of the optical wave is arranged at the downlink Si straight waveguide (8) The uplink composite waveguide (5) and the downlink composite waveguide (7) are formed by depositing a layer of phase change material film (11) on the Si waveguide (10); (2) Preparation of waveguide structure A SiO2 substrate material is covered with photoresist, and a focused electron beam exposure process is used to prepare a Si waveguide (10) having three Si straight waveguides and two composite waveguides on the substrate according to the waveguide structure designed in step (1); (3) Integration of phase change materials The waveguide structure obtained in step (2) is subjected to photoresist spin coating, and the Si waveguide (10) of the composite waveguide is subjected to electron beam exposure, and then a multi-component sulfide phase change film (11) with a thickness of 10 to 300 nanometers is deposited on the Si waveguide (10) of the composite waveguide by a magnetron sputtering process; the magnetron sputtering process parameters include: an Ar gas flow rate of 50 sccm, a sulfide target sputtering power of 20 to 50 W, a sputtering pressure of 0.8 to 1.2 Pa, and a sputtering time of 2 to 10 minutes; the sulfide target is any two or more of Ge, Sb, Se and Te elements; (4) The photoresist is stripped off to obtain a multi-mode switching 1×3 optical switch based on chalcogenide phase change material.

2. The method for preparing a multi-mode switching 1×3 type optical waveguide switch based on phase change material according to claim 1, characterized in that: The thickness of the substrate is 1 micrometer to 100 micrometers.

3. The method for preparing a multi-mode switching 1×3 type optical waveguide switch based on phase change material according to claim 1, characterized in that: The thickness of the middle Si straight waveguide (6), the uplink Si straight waveguide (4) and the downlink Si straight waveguide (8) is 100-400 nanometers, the width is 200-600 nanometers, 600-1100 nanometers and 1100-1900 nanometers respectively, and the length is 10-80 micrometers, 20-80 micrometers and 10-30 micrometers respectively.

4. The method for preparing a multi-mode switching 1×3 type optical waveguide switch based on phase change material according to claim 1, characterized in that: The width of the uplink composite waveguide (5) and the downlink composite waveguide (7) is 200-600 nanometers, and the length is 5-30 micrometers; the thickness of their Si waveguide (10) is 100-400 nanometers, and the thickness of the phase change material film layer (11) is 10-100 nanometers.

5. The method for preparing a multi-mode switching 1×3 type optical waveguide switch based on phase change material according to claim 1, characterized in that: The distance between each waveguide is 100 to 200 nanometers.

6. A multi-mode switching 1×3 type optical waveguide switch based on phase change material obtained by the preparation method of claim 1.

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