A phase change material based slotted waveguide optical switch

Abstract

A slit waveguide optical switch based on phase change materials, belonging to the field of optoelectronic modulation technology, is used to solve the problem that silicon-based optical switches based on thermo-optical effects and carrier dispersion effects cannot simultaneously achieve low power consumption, compact size, wide operating bandwidth, and low insertion loss. The optical switch includes an incident region, a slit modulation region, and an exit region connected sequentially along the optical transmission path. The first S-shaped slit, the rectangular slit, and the second S-shaped slit are connected sequentially. The incident tapered silicon waveguide, the rectangular vanadium dioxide waveguide, and the exit tapered silicon waveguide are connected sequentially. The incident curved silicon waveguide, the rectangular silicon waveguide, and the exit curved silicon waveguide are connected sequentially, forming a coupling waveguide. The S-shaped slit waveguide structure reduces the coupling loss caused by the optical signal entering and exiting the slit waveguide. The modulation function is achieved by applying external electrical excitation to cause a phase change in vanadium dioxide. This results in a compact size, low insertion loss, and good process tolerance.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic modulation technology and relates to a slit waveguide optical switch based on phase change material. Background Technology

[0002] With the development of large-scale integrated circuits, the demand for data transmission in fields such as communication, computing, and sensing has increased significantly. Traditional electrical interconnect technologies are facing bottlenecks such as power consumption, capacity, and electromagnetic interference. Silicon-based optoelectronic interconnects, as an emerging technology, can utilize the properties of photons to achieve high-speed, high-bandwidth on-chip data transmission and processing, effectively solving the problems faced by electrical interconnects and providing a new alternative for traditional electrical interconnect data transmission. Furthermore, silicon-based optoelectronic interconnects have been proven to be able to realize high-density photonic integrated circuits using manufacturing processes compatible with Complementary Metal-Oxide-Semiconductor (CMOS), enabling existing CMOS manufacturing processes to mass-produce photonic integrated circuits at low cost.

[0003] Optical switches are a crucial component of photonic integrated circuits, used for switching, routing, and optical cross-connection, and have wide applications in optical communication networks, optical computing, and sensing. Existing silicon-integrated optical switches include various types, primarily classified by switch structure as micro-ring resonator (MRR) type, Mach-Zehnder interferometer (MZI) type, and hybrid types combining MRR and MZI. Key parameters of silicon-based integrated optical switches include switching speed, bandwidth, power consumption, extinction ratio, insertion loss, crosstalk, and footprint. These design parameters have different requirements for different applications: for example, optical interconnect applications typically require wide bandwidth and wavelength selectivity to support high-speed data transmission and provide routing flexibility; while for optical computing applications, due to the need for more frequent switching operations, power consumption and switching speed are critical.

[0004] Silicon-based waveguide optical switches typically employ thermo-optical effects or carrier dispersion effects to alter the refractive index of the material, enabling reconfigurable signal routing. Thermo-optical effects change the refractive index by introducing heat into the waveguide; however, the propagation and dissipation of heat takes time, resulting in high power consumption and low switching speeds. Carrier dispersion effects, on the other hand, are weaker effects that change the refractive index by injecting carriers into the waveguide, resulting in smaller refractive index changes and larger device lengths. Both effects are volatile; without continuous energy input, the device gradually returns to its initial state, requiring continuous energy input to maintain its state, further increasing switching power consumption. Therefore, traditional silicon-based optical switches based on thermo-optical and carrier dispersion effects remain challenging in achieving low power consumption, compact size, wide operating bandwidth, and low insertion loss.

[0005] To overcome the aforementioned shortcomings, phase change materials (PCMs) have been introduced into the field of silicon-based optoelectronics. As a unique material, PCMs exhibit significant changes in non-volatility and optical properties under external stimuli such as temperature, applied voltage, or ultrafast optical excitation. For example, the invention patent with publication number CN117742013A proposes a tunable silicon optical polarizer based on PCMs, utilizing the significant difference in optical properties exhibited by the PCM before and after heating to achieve the tunability of the polarizer. Vanadium dioxide (VO2), a commonly used PCM material in silicon integrated optical switches, is a thermally tunable phase change metal oxide capable of undergoing a reversible transition from an insulating phase to a metallic phase at around 68°C, accompanied by reversible changes in optical, electrical, and magnetic properties. This transition can also be triggered by light pulses or electricity. From a crystal structure perspective, VO2 transforms from a monoclinic state at low temperatures to a tetragonal state at high temperatures. Utilizing the above characteristics, the real and imaginary parts of the PCM refractive index can be transformed by external excitation, enabling the design of waveguide optical switches with low power consumption and small footprint.

[0006] Therefore, proposing a silicon-based waveguide optical switch that can achieve low power consumption, compact size, wide operating bandwidth and low insertion loss based on phase change materials has important technical significance and application prospects, and can provide a new solution for the development of optical communication technology and the expansion of optoelectronic applications. Summary of the Invention

[0007] The technical solution of this invention is used to solve the problem that silicon-based optical switches based on thermo-optical effect and carrier dispersion effect are difficult to achieve simultaneously low power consumption, compact size, wide operating bandwidth and low insertion loss.

[0008] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0009] A slit waveguide optical switch based on phase change material includes a silicon dioxide cladding layer, an optical switch, a silicon dioxide buried layer, and a silicon substrate layer; the optical switch includes an incident region, a slit modulation region, and an exit region connected sequentially along the optical transmission path.

[0010] The incident region includes an incident conical silicon waveguide, an incident curved silicon waveguide, and a first S-shaped slit; the two incident curved silicon waveguides are symmetrically distributed along the centerline of the incident conical silicon waveguide, and respectively form the first S-shaped slit with the two sides of the incident conical silicon waveguide;

[0011] The slit modulation region includes a rectangular vanadium dioxide, a rectangular silicon waveguide, and a rectangular slit; the two rectangular silicon waveguides are symmetrically distributed about the center line of the rectangular vanadium dioxide along the optical transmission path, forming rectangular slits with the two sides of the rectangular vanadium dioxide respectively.

[0012] The emission region includes an emission tapered silicon waveguide, an emission curved silicon waveguide, and a second S-shaped slit; the two emission curved silicon waveguides are symmetrically distributed along the centerline of the emission tapered silicon waveguide, and respectively form the second S-shaped slit with the two sides of the emission tapered silicon waveguide.

[0013] The first S-shaped slit, the rectangular slit, and the second S-shaped slit are connected in sequence; the incident conical silicon waveguide, the rectangular vanadium dioxide waveguide, and the exiting conical silicon waveguide are connected in sequence; the incident curved silicon waveguide, the rectangular silicon waveguide, and the exiting curved silicon waveguide are connected in sequence to form a coupling waveguide.

[0014] Furthermore, the incident conical silicon waveguide and the outgoing conical silicon waveguide have the same structure, and are symmetrically distributed with rectangular vanadium dioxide along the center line perpendicular to the light transmission path.

[0015] Furthermore, the incident curved silicon waveguide and the exit curved silicon waveguide have the same structure, and are symmetrically distributed with rectangular vanadium dioxide along the center line perpendicular to the light transmission path.

[0016] Furthermore, the top output end of the incident conical silicon waveguide is connected to the input end of the rectangular vanadium dioxide, and the output end of the rectangular vanadium dioxide is connected to the top input end of the exiting conical silicon waveguide. The optical signal enters the optical switch from the bottom input end of the incident conical silicon waveguide and exits the optical switch from the bottom output end of the exiting conical silicon waveguide.

[0017] Furthermore, the incident conical silicon waveguide has the same length as the incident curved silicon waveguide, which is 3 μm; the bottom width of the incident conical silicon waveguide is 450 nm and the top width is 130 nm; the input width of the incident curved silicon waveguide is 100 nm and the output width is 260 nm.

[0018] Furthermore, the rectangular vanadium dioxide and the rectangular silicon waveguide have the same length, which is 2 μm; the width of the rectangular vanadium dioxide is 130 nm; and the width of the rectangular silicon waveguide is 260 nm.

[0019] Furthermore, the first S-shaped slit, the rectangular slit, and the second S-shaped slit have the same width of 50 nm; the first S-shaped slit and the second S-shaped slit have the same length of 3 μm; and the rectangular slit has a length of 2 μm.

[0020] Furthermore, the optical switch has a length of 8μm, a width of 750nm, and a height of 220nm.

[0021] Furthermore, the upper part of the optical switch is covered by a silicon dioxide upper cladding layer, the lower part of the optical switch is disposed on the upper surface of the silicon dioxide buried layer, the optical switch is sandwiched between the silicon dioxide upper cladding layer and the silicon dioxide buried layer, and the lower surface of the silicon dioxide buried layer is attached to the upper surface of the silicon substrate layer.

[0022] Furthermore, when the rectangular vanadium dioxide is the insulating phase, the optical signal passes through the slit modulation region with low transmission loss, and the optical switch is in the "on" state; when the rectangular vanadium dioxide is the metallic phase, the extinction coefficient of the metallic phase is much greater than that of the insulating phase, and at the same time, the interface between vanadium dioxide and the slit medium will excite the surface plasma effect, which enhances the absorption effect of vanadium dioxide on the optical signal, increases the optical signal transmission loss, and the optical switch is in the "off" state.

[0023] The advantages of this invention are:

[0024] (1) The present invention utilizes the design of slit waveguide to effectively limit the transmission of optical signals inside the waveguide, reduce scattering and loss at the waveguide boundary, and has low transmission loss.

[0025] (2) The present invention reduces the coupling loss of optical signals entering and exiting the slit waveguide by using an S-shaped slit waveguide structure, compared with the method of direct coupling using a strip waveguide.

[0026] (3) The present invention uses a slit modulation region formed by mixing vanadium dioxide and silicon waveguide to achieve modulation function by applying external electrical excitation to cause vanadium dioxide to undergo phase change. Taking advantage of the high concentration of light energy in the slit waveguide, the light signal can generate a stronger interaction with the phase change material when propagating in the slit. The optical switch using this characteristic can effectively improve the switching contrast.

[0027] (4) The slit waveguide optical switch design of the present invention can maintain the overall performance of the switch within the ideal range when it changes due to process errors, and has a good process fault tolerance.

[0028] (5) This invention achieves an extinction ratio of 10.29dB and an insertion loss of 1.86dB at a working wavelength of 1500nm using a slit waveguide optical switch structure with a size of 8μm×750nm. It achieves compact size and low insertion loss, which has important technical significance and application prospects. Attached Figure Description

[0029] Figure 1 This is an overall structural diagram of a slit waveguide optical switch based on phase change material according to an embodiment of the present invention;

[0030] Figure 2 This is an exploded view of a slit waveguide optical switch based on phase change material according to an embodiment of the present invention;

[0031] Figure 3 This is a structural diagram of an optical switch based on a slit waveguide optical switch using phase change materials according to an embodiment of the present invention.

[0032] Figure 4 This is a top view of the optical switch based on a slit waveguide optical switch using phase change materials according to an embodiment of the present invention.

[0033] Figure 5 This is a distribution diagram of the optical switching working field of rectangular vanadium dioxide in different phase states according to an embodiment of the present invention;

[0034] Figure 6 These are simulation results of the optical switch performance of the slit modulation region under different geometric parameters according to an embodiment of the present invention;

[0035] Figure 7 This is a schematic diagram of the slit modulation region under different process errors according to an embodiment of the present invention;

[0036] Figure 8 This is a simulation result diagram of the optical switch performance of the slit modulation region under different process errors according to an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0039] Example 1

[0040] Slit waveguides are a special type of waveguide structure, characterized by their small size, high integration, low transmission loss, and high sensitivity. Due to their small size, they are suitable for design and fabrication at the micro- and nanoscale, enabling highly integrated optical devices and thus improving device integration.

[0041] like Figure 1-2 As shown, specifically, the present invention discloses a slit waveguide optical switch based on phase change material, including a silicon dioxide cladding layer 1, an optical switch 2, a silicon dioxide buried layer 3, and a silicon substrate layer 4; the optical switch 2 includes an incident region 21, a slit modulation region 22, and an exit region 23 connected sequentially along the optical transmission path.

[0042] like Figure 1-2 As shown, the upper part of the optical switch 2 is covered by the silicon dioxide upper cladding layer 1, and the lower part of the optical switch 2 is disposed on the upper surface of the silicon dioxide buried layer 3. The optical switch 2 is sandwiched between the silicon dioxide upper cladding layer 1 and the silicon dioxide buried layer 3. The lower surface of the silicon dioxide buried layer 3 is attached to the upper surface of the silicon substrate layer 4.

[0043] like Figure 3-4 As shown, the incident region 21 includes an incident conical silicon waveguide 211, an incident curved silicon waveguide 212, and a first S-shaped slit 213; the two incident curved silicon waveguides 212 are symmetrically distributed along the centerline axis of the incident conical silicon waveguide 211, forming the first S-shaped slit 213 with both sides of the incident conical silicon waveguide 211. The slit modulation region 22 includes a rectangular vanadium dioxide 221, a rectangular silicon waveguide 222, and a rectangular slit 223; the two rectangular silicon waveguides 222 are symmetrically distributed along the centerline axis of the rectangular vanadium dioxide 221 along the optical transmission path direction, forming the rectangular slit 223 with both sides of the vanadium dioxide 221. The emission region 23 includes an emission tapered silicon waveguide 231, an emission curved silicon waveguide 232, and a second S-shaped slit 233; the two emission curved silicon waveguides 232 are symmetrically distributed along the centerline of the emission tapered silicon waveguide 231, and form the second S-shaped slit 233 with the two sides of the emission tapered silicon waveguide 231 respectively.

[0044] The first S-shaped slit 213, the rectangular slit 223, and the second S-shaped slit 233 are sequentially connected; the incident conical silicon waveguide 211, the rectangular vanadium dioxide waveguide 221, and the exiting conical silicon waveguide 231 are sequentially connected; the incident curved silicon waveguide 212, the rectangular silicon waveguide 222, and the exiting curved silicon waveguide 232 are sequentially connected, forming a coupling waveguide. Since the optical switch 2 is entirely encased by the silicon dioxide cladding 1 and the silicon dioxide buried layer 3, the slits formed within the optical switch 2 are filled with silicon dioxide as the slit medium.

[0045] In this invention, the slit waveguide effectively confines the propagation of optical signals within the waveguide, reducing scattering and loss at the waveguide boundary and resulting in lower transmission loss. Due to the small overall size of waveguide optical switch devices and the significant difference in mode distribution between strip waveguides and slit waveguides in traditional technologies, direct coupling using strip waveguides leads to substantial losses in the input and output modulation regions. This invention reduces coupling loss by forming an S-shaped slit waveguide optical switch structure, utilizing the S-shaped slit for entry and exit from the input and output regions. Simultaneously, the slit modulation region is composed of a mixture of rectangular vanadium dioxide and rectangular silicon waveguides, forming a slit. Modulation is achieved by applying external electrical excitation to induce a phase transition in VO2. Utilizing the highly concentrated light energy within the slit waveguide, the optical signal propagating in the slit can interact more strongly with the phase-change material, effectively improving the switching contrast of the optical switch.

[0046] The incident tapered silicon waveguide 211 and the exit tapered silicon waveguide 231 have the same structure, and are symmetrically distributed with respect to the centerline axis of the rectangular vanadium dioxide 221 along the direction perpendicular to the light transmission path. The incident curved silicon waveguide 212 and the exit curved silicon waveguide 232 have the same structure, and are symmetrically distributed with respect to the centerline axis of the rectangular vanadium dioxide 221 along the direction perpendicular to the light transmission path. Specifically, the incident region 21 and the exit region 23 are symmetrically distributed with respect to the centerline axis of the rectangular vanadium dioxide 221 along the direction perpendicular to the light transmission path.

[0047] The top output terminal of the incident tapered silicon waveguide 211 is connected to the input terminal of the rectangular vanadium dioxide 221, and the output terminal of the rectangular vanadium dioxide 221 is connected to the top input terminal of the exiting tapered silicon waveguide 231. The optical signal enters the optical switch 2 from the bottom input terminal of the incident tapered silicon waveguide 211 and exits the optical switch 2 from the bottom output terminal of the exiting tapered silicon waveguide 231. In this embodiment, an incident optical signal with a wavelength of 1550 nm enters the slit modulation region 22 through the incident tapered silicon waveguide 211, and the modulated optical signal is output from the exiting tapered silicon waveguide 231.

[0048] like Figure 3-4 As shown, the optical switch 2 has a length of 8 μm, a width of 750 nm, and a height of 220 nm. The incident region 21, the slit modulation region 22, and the exit region 23 all have the same height and width: 220 nm and 750 nm, respectively. The incident region 21 has the same length as the exit region 23, which is 3 μm. The slit modulation region 22 has a length of 2 μm.

[0049] Specifically, the incident conical silicon waveguide 211 and the incident curved silicon waveguide 212 have the same length, which is 3μm; the bottom width of the incident conical silicon waveguide 211 is 450nm and the top width is 130nm; the input width of the incident curved silicon waveguide 212 is 100nm and the output width is 260nm.

[0050] The rectangular vanadium dioxide 221 and the rectangular silicon waveguide 222 have the same length, which is 2μm; the width of the rectangular vanadium dioxide 221 is 130nm; and the width of the rectangular silicon waveguide 222 is 260nm.

[0051] The first S-shaped slit 213, the rectangular slit 223, and the second S-shaped slit 233 have the same width of 50 nm; the first S-shaped slit 213 and the second S-shaped slit 233 have the same length of 3 μm; and the rectangular slit 223 has a length of 2 μm.

[0052] Working principle:

[0053] like Figure 4 As shown, incident light with a wavelength of 1550 nm enters the incident region 21. The incident conical silicon waveguide 211 and the incident curved silicon waveguide 212 form a curved first S-shaped slit 213, which introduces the optical signal into the slit modulation region 2, i.e., the region where the rectangular vanadium dioxide 221 is located, with high transmission efficiency. Vanadium dioxide, or VO2, as a phase change material, has unique optical properties, exhibiting a transformation from an insulating phase to a metallic phase at around 68°C. At low temperatures, VO2 is in an insulating phase and transparent to infrared light; conversely, it is in a metallic phase and absorbs infrared light.

[0054] In the slit modulation region formed by VO2 and a rectangular silicon waveguide, when VO2 is in the insulating phase, the optical signal is transmitted through the coupling region with low loss, and optical switch 2 is in the "on" state. When VO2 is transformed into the metallic phase by external electric field excitation, on the one hand, the extinction coefficient of VO2 in the metallic phase is much greater than that in the insulating phase; on the other hand, the interface between vanadium dioxide and the slit medium will excite the surface plasmon effect. Due to the strong absorption of the optical signal by VO2 in the slit, the surface plasmon effect enhances the absorption effect of VO2 on the optical signal, resulting in huge optical signal transmission loss, i.e., optical switch 2 is in the "off" state.

[0055] When VO2 is in different phase states, the operating field distribution of the optical switch is as follows: Figure 5 As shown. When VO2 is the insulating phase, its refractive index is similar to that of a silicon waveguide, and the extinction coefficient of the insulating phase VO2 is low, resulting in relatively low absorption of optical signals. Therefore, most of the light can be coupled out through the modulation region to form an optical switch, such as... Figure 5 As shown in (a), the insertion loss is 1.86 dB. When VO2 is a metallic phase, it exhibits metallic reflective properties. Figure 5 As shown in (b), the optical signal coupled into the modulation region will be significantly reflected. Figure 5 (c) and Figure 5(d) It can be seen that the transmission mode of the optical signal in the overall structure is almost unaffected. A small amount of light in the modulation region is uniformly distributed in VO2 and the silicon waveguides on both sides, while most of the light is confined to the slit for transmission. Furthermore, Figure 5 (d) shows that when VO2 is a metallic phase, more light is confined to the slit for transmission compared to the modulation region of the insulating phase. The light in the slits on both sides is exhausted due to the huge absorption of the metallic phase VO2, resulting in only a small amount of light being coupled out of the optical switch. At this time, the insertion loss is 12.15dB, that is, the extinction ratio of the proposed slit waveguide optical switch is 10.29dB.

[0056] In this embodiment, when the slot width remains constant, such as Figure 6 As shown in (a) and (b), the insertion loss and extinction ratio of the slit waveguide optical switch both exhibit a monotonically increasing trend with the increase of the length and width of VO2. With the increase of the size of the modulation region VO2, the intensity of the optical signal absorbed when transmitting through the modulation region increases in both the insulating and metallic phases, leading to an increase in insertion loss in both phases. The extinction coefficients of VO2 differ significantly between the two phases; the absorption efficiency of VO2 in the metallic phase is much greater than that in the insulating phase, so the extinction ratio also increases with the increase of the VO2 size. When the geometric dimensions of the modulation region VO2 remain constant, such as... Figure 6 As shown in (c), both insertion loss and extinction ratio gradually decrease with increasing slit width. On one hand, as the slit width increases, the light energy density within the slit decreases, leading to a reduction in the interaction between light and VO2. Therefore, the insertion loss decreases with increasing slit width. On the other hand, the absorption efficiency of VO2 metal phase is much higher than that of the insulating phase. Therefore, the reduction in light interaction between the metal phase and VO2 due to increased slit width is greater than that of the insulating phase, resulting in a lower extinction ratio. After comprehensively considering modulation efficiency and structural dimensions, the slit width was ultimately determined to be constant at 50 nm, and the rectangular vanadium dioxide 221 had a length of 2 μm and a width of 130 nm.

[0057] This embodiment also analyzes the working performance of the optical switch under different process errors. Since there is a possibility of errors in the manufacturing process of the slit waveguide optical switch structure, the present invention also comprehensively considers the impact of the following process errors on the working performance of the optical switch.

[0058] like Figure 7 As shown in (a), the length of the rectangular vanadium dioxide 221 in the slit modulation region may be less than 2 μm, resulting in a certain gap between the incident tapered silicon waveguide 211, the exiting tapered silicon waveguide 231, and the rectangular vanadium dioxide 221; as Figure 7As shown in (b), the rectangular vanadium dioxide 221 has a length exceeding 2 μm, with the excess portion covering the ends of adjacent silicon waveguides; and within the slot modulation region 2, the rectangular vanadium dioxide 221 will be offset perpendicular to the optical transmission direction. The simulation analysis results of the above three effects on the optical switch process performance are as follows: Figure 8 As shown, under the three process error conditions, the insertion loss and extinction ratio tend to stabilize without significant changes. Therefore, this invention has good process tolerance. Even when the VO2 size changes due to process errors, the overall switching performance of this invention remains within the ideal range.

[0059] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A slit waveguide optical switch based on phase change material, characterized in that, It includes a silicon dioxide cladding layer (1), an optical switch (2), a silicon dioxide buried layer (3), and a silicon substrate layer (4); the optical switch (2) includes an incident area (21), a slit modulation area (22), and an exit area (23) connected sequentially along the light transmission path; The incident region (21) includes an incident conical silicon waveguide (211), an incident curved silicon waveguide (212), and a first S-shaped slit (213); the two incident curved silicon waveguides (212) are symmetrically distributed along the centerline of the incident conical silicon waveguide (211), and respectively form the first S-shaped slit (213) with the two sides of the incident conical silicon waveguide (211); The slit modulation region (22) includes a rectangular vanadium dioxide (221), a rectangular silicon waveguide (222), and a rectangular slit (223); the two rectangular silicon waveguides (222) are symmetrically distributed about the center line of the rectangular vanadium dioxide (221) along the optical transmission path, and form rectangular slits (223) with the two sides of the rectangular vanadium dioxide (221) respectively. The emission region (23) includes an emission tapered silicon waveguide (231), an emission curved silicon waveguide (232), and a second S-shaped slit (233); the two emission curved silicon waveguides (232) are symmetrically distributed along the centerline of the emission tapered silicon waveguide (231), and form the second S-shaped slit (233) with the two sides of the emission tapered silicon waveguide (231), respectively; The first S-shaped slit (213), the rectangular slit (223), and the second S-shaped slit (233) are connected in sequence; the incident conical silicon waveguide (211), the rectangular vanadium dioxide waveguide (221), and the exiting conical silicon waveguide (231) are connected in sequence; the incident curved silicon waveguide (212), the rectangular silicon waveguide (222), and the exit curved silicon waveguide (232) are connected in sequence to form a coupling waveguide.

2. The slit waveguide optical switch based on phase change material according to claim 1, characterized in that, The incident conical silicon waveguide (211) has the same structure as the outgoing conical silicon waveguide (231), with rectangular vanadium dioxide (221) symmetrically distributed along the centerline of the direction perpendicular to the light transmission path.

3. The slit waveguide optical switch based on phase change material according to claim 2, characterized in that, The incident curved silicon waveguide (212) has the same structure as the outgoing curved silicon waveguide (232), with rectangular vanadium dioxide (221) symmetrically distributed along the center line of the direction perpendicular to the light transmission path.

4. The slit waveguide optical switch based on phase change material according to claim 3, characterized in that, The top output end of the incident conical silicon waveguide (211) is connected to the input end of the rectangular vanadium dioxide (221), and the output end of the rectangular vanadium dioxide (221) is connected to the top input end of the exiting conical silicon waveguide (231). The optical signal enters the optical switch (2) from the bottom input end of the incident conical silicon waveguide (211) and exits the optical switch (2) from the bottom output end of the exiting conical silicon waveguide (231).

5. The slit waveguide optical switch based on phase change material according to claim 3, characterized in that, The incident conical silicon waveguide (211) and the incident curved silicon waveguide (212) have the same length, which is 3 μm. The bottom width of the incident conical silicon waveguide (211) is 450 nm and the top width is 130 nm. The input width of the incident curved silicon waveguide (212) is 100 nm and the output width is 260 nm.

6. The slit waveguide optical switch based on phase change material according to claim 3, characterized in that, The rectangular vanadium dioxide (221) and the rectangular silicon waveguide (222) have the same length, which is 2 μm; the width of the rectangular vanadium dioxide (221) is 130 nm; and the width of the rectangular silicon waveguide (222) is 260 nm.

7. The slit waveguide optical switch based on phase change material according to claim 3, characterized in that, The first S-shaped slit (213), the rectangular slit (223), and the second S-shaped slit (233) have the same width of 50 nm; the first S-shaped slit (213) and the second S-shaped slit (233) have the same length of 3 μm; the rectangular slit (223) has a length of 2 μm.

8. The slit waveguide optical switch based on phase change material according to claim 1, characterized in that, The optical switch (2) has a length of 8μm, a width of 750nm, and a height of 220nm.

9. The slit waveguide optical switch based on phase change material according to claim 1, characterized in that, The upper part of the optical switch (2) is covered by a silicon dioxide cladding layer (1), and the lower part of the optical switch (2) is disposed on the upper surface of the silicon dioxide buried layer (3). The optical switch (2) is sandwiched between the silicon dioxide cladding layer (1) and the silicon dioxide buried layer (3). The lower surface of the silicon dioxide buried layer (3) is attached to the upper surface of the silicon substrate layer (4).

10. The slit waveguide optical switch based on phase change material according to claim 1, characterized in that, When the rectangular vanadium dioxide (221) is an insulating phase, the optical signal passes through the slit modulation region (22) with low transmission loss, and the optical switch (2) is in the "on" state; when the rectangular vanadium dioxide (221) is a metallic phase, the extinction coefficient of the metallic phase is much greater than that of the insulating phase, and at the same time, the interface between vanadium dioxide and the slit medium will excite the surface plasma effect, which enhances the absorption effect of vanadium dioxide on the optical signal, increases the optical signal transmission loss, and the optical switch (2) is in the "off" state.

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