Bent waveguide based on optical phase change material and power adjusting method and preparation method thereof

Abstract

The invention discloses a bent waveguide based on an optical phase change material. The bent waveguide comprises a substrate layer and a device layer, the device layer is arranged on the substrate layer; the device layer comprises a sub-wavelength grating structure, a bus waveguide and a bent waveguide; the bus waveguide comprises an input area waveguide and an output area waveguide, the output end of the input area waveguide is connected with the input end of the bent waveguide, the output end of the bent waveguide is connected with the input end of the output area waveguide, and the sub-wavelength grating structures are located on the output end side of the input area waveguide and the input end side of the output area waveguide respectively; the sub-wavelength grating structure is composed of a plurality of sub-structures and is used for matching light propagation modes of the straight waveguide section and the bent waveguide section. According to the power regulation scheme, additional regulation components are not needed, function integration is achieved through the sub-wavelength grating structure of the bent waveguide and the characteristics of the phase change material, the chip structure is simplified, the integration complexity is reduced, additional loss caused by additional components is avoided, and the development requirement of integrated photonics is met.

Description

Technical Field

[0001] This invention relates to the field of integrated photonics, and in particular to a bent waveguide based on optical phase change materials. Background Technology

[0002] Integrated photonics is a cutting-edge discipline that miniaturizes and integrates optical devices. Relying on semiconductor micro / nano fabrication technology, it integrates multiple optical functional devices onto a single chip. Currently, with the increasing density of photonic integration, waveguide bending is inevitable. However, once a waveguide bends, its optical field will exhibit varying degrees of leakage. Achieving low-loss bending within a small size becomes a problem that needs to be solved. Typically, the losses introduced by waveguide bending come from: 1. Light field scattering caused by roughness of the waveguide sidewalls; 2. Mode mismatch between straight and bent waveguides; and 3. Light field radiation caused by phase mismatch between the inner and outer sides of the bent waveguide structure. Especially when the size of the bent waveguide becomes smaller (approaching 5 micrometers), the energy losses caused by the second and third problems will increase significantly. Therefore, reasonable device design is needed to reduce waveguide bending losses. Furthermore, existing bent waveguide fabrication is based on micro / nano fabrication processes, and its structure cannot be changed once fabricated, meaning the device's function is also immutable. Currently, it is almost impossible to adjust the output optical power in existing bent waveguides.

[0003] For waveguide bending, Euler-bent waveguides and Bessel-bent waveguides have addressed the issues of size and loss to varying degrees. However, Euler-bent and Bessel-bent structures are difficult to apply when the bending radius is close to 5 micrometers. For phase change materials, Sb₂Se₃ is selected. This material has a crystalline refractive index of 4.05 and an amorphous refractive index of 3.28 at a communication wavelength of 1.55 micrometers. The imaginary part of the refractive index in both states is close to zero, corresponding to extremely low material absorption loss, which is beneficial for low-loss on-chip transmission. Simultaneously, its phase transition temperature is 200℃ (from amorphous to crystalline) and its melting temperature is 620℃ (from crystalline to amorphous). Therefore, how to utilize phase change material substrates to realize small-size (5 micrometers), low-loss, and tunable output power bent waveguides is a key research focus, and it has significant practical implications for promoting the development of on-chip photonic integrated circuits towards high-density, large-scale integration. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is that Euler bending and Bezier bending structures are difficult to apply when the bending radius is close to 5 micrometers.

[0005] The above-mentioned technical problems are solved by the following technical solution: The present invention proposes a curved waveguide based on optical phase change material, which includes a substrate layer and a device layer;

[0006] The device layer is disposed on the substrate layer;

[0007] The device layer includes a subwavelength grating structure, a bus waveguide, and a bent waveguide;

[0008] The bus waveguide includes an input waveguide and an output waveguide. The output end of the input waveguide is connected to the input end of the curved waveguide, and the output end of the curved waveguide is connected to the input end of the output waveguide.

[0009] The subwavelength grating structures are located at the output end of the input waveguide and the input end of the output waveguide, respectively; the subwavelength grating structure is composed of multiple substructures and is used to match the optical propagation modes of the straight waveguide section and the curved waveguide section.

[0010] In a preferred embodiment of the curved waveguide based on optical phase change material described in this invention: the substructure of the subwavelength grating structure is an isosceles triangle, with the base of the isosceles triangle located inside the waveguide and the vertex located outside the waveguide;

[0011] The center-to-center distance between two adjacent isosceles triangles is N1, and the value of N1 ranges from 0.08 to 0.12 micrometers.

[0012] The distance between the isosceles triangle closest to the output end of the input waveguide or the input end of the output waveguide and the corresponding waveguide end is N2, and the value of N2 ranges from 0.08 to 0.12 micrometers.

[0013] In a preferred embodiment of the curved waveguide based on optical phase change material described in this invention: the base length of the isosceles triangle is 0.1~0.2 micrometers, and the height is 1.0~1.5 micrometers; the total number of substructures of the subwavelength grating structure is 15~30.

[0014] In a preferred embodiment of the curved waveguide based on optical phase change material of the present invention: the phase change material of the subwavelength grating structure is an amorphous structure, and the phase change materials of the bus waveguide and the curved waveguide are crystalline structures.

[0015] In a preferred embodiment of the curved waveguide based on optical phase change material of the present invention: the width of the bus waveguide and the curved waveguide is 1.0~1.5 micrometers, the length along the waveguide extension direction is 8~12 micrometers, and the thickness is 80~120 nanometers; the thickness of the phase change material layer of the subwavelength grating structure is 80~120 nanometers.

[0016] In a preferred embodiment of the curved waveguide based on optical phase change material of the present invention: the substrate layer includes a first dielectric layer and a second dielectric layer, the second dielectric layer being located on the first dielectric layer; the first dielectric layer is a silicon dioxide layer with a thickness of 1.5~2.5 micrometers; the second dielectric layer is a silicon nitride layer with a thickness of 250~350 nanometers.

[0017] In a preferred embodiment of the curved waveguide based on optical phase change material described in this invention: the curved waveguide is a circular arc curved structure with a bending radius of 4.5~5.5 micrometers; the bending radius of the outer waveguide wall is larger than that of the inner waveguide wall.

[0018] The present invention also proposes a power adjustment method for the above-mentioned curved waveguide based on optical phase change material, characterized in that: by adjusting the number of substructures of the subwavelength grating structure, the coupling degree of the optical propagation mode between the straight waveguide section and the curved waveguide section is changed, thereby controlling the output optical power;

[0019] The number of substructures can be adjusted from N to 0, where N is an integer from 15 to 30.

[0020] In a preferred embodiment of the power adjustment method of the present invention: the method of adjusting the number of substructures is: from the input end near the input region waveguide or the output end of the output region waveguide, the substructures of the subwavelength grating structure are erased or written sequentially in the direction of the curved waveguide.

[0021] The number of subwavelength grating substructures on the input waveguide side and the output waveguide side is adjusted synchronously.

[0022] This invention also proposes a method for fabricating a bent waveguide based on optical phase change materials as described above, comprising the following steps:

[0023] A phase change material layer is deposited on the surface of the second dielectric layer of the substrate using magnetron sputtering. The initial state of the phase change material layer is amorphous.

[0024] An antioxidant protective layer is deposited on the surface of the phase change material layer;

[0025] Pulsed lasers are used to write the input waveguide, curved waveguide, and output waveguide of a crystalline state;

[0026] Amorphous subwavelength grating structures are written using pulsed lasers at the output end of the waveguide in the input region and the input end of the waveguide in the output region.

[0027] The beneficial effects of this invention are as follows: Compared with the prior art, this power regulation scheme does not require additional regulation components such as attenuators and modulators. It directly utilizes the subwavelength grating structure and phase change material characteristics of the curved waveguide itself to achieve functional integration, which simplifies the chip structure, reduces integration complexity, and avoids additional losses introduced by additional components, thus meeting the development needs of integrated photonics. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Wherein:

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0030] Figure 2 The cross-sectional structure of the waveguides in the input and output regions;

[0031] Figure 3 A magnified view of the subwavelength grating structure in the input region;

[0032] Figure 4 Optical field transmission diagram without the introduction of subwavelength structure;

[0033] Figure 5 The optical field transmission diagram is shown when 23 subwavelength structures are used.

[0034] Figure 6 The transmittance curve is shown when the number of subwavelength structures is reduced from 23 to 0.

[0035] Figure 7 The transmittance curve is shown when the number of subwavelength structures is reduced from 30 to 0. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0037] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0038] Reference Figures 1 to 7This embodiment provides a bent waveguide based on an optical phase change material, including a substrate layer and a device layer;

[0039] The device layer is disposed on the substrate layer; specifically, the phase change material of the device layer is a low absorption loss optical phase change material, specifically Sb2Se3. This material has a crystalline refractive index of 4.05 and an amorphous refractive index of 3.28 in the 1500~1600 nm communication wavelength band, preferably at the 1550 nm communication wavelength. Moreover, the imaginary part of the refractive index in both states is close to zero, corresponding to extremely low material absorption loss, which can fully meet the requirements of low-loss on-chip transmission of optical signals. At the same time, Sb2Se3 has stable phase change characteristics, with a phase change temperature of 200℃ from amorphous to crystalline and a melting temperature of 620℃ from crystalline to amorphous.

[0040] The device layer includes a subwavelength grating structure 21, a bus waveguide 22, and a bent waveguide 23; specifically, the bent waveguide 23 is a 90° turning structure, used to realize the 90° turning transmission of optical signals, thereby facilitating the spatial layout in the photonic chip.

[0041] The bus waveguide 22 includes an input waveguide 22a and an output waveguide 22b. The output end of the input waveguide 22a is connected to the input end of the curved waveguide 23, and the output end of the curved waveguide 23 is connected to the input end of the output waveguide 22b. The output end of the curved waveguide 23 and the input end of the output waveguide 22b are directly connected. The three together form a complete transmission path for the optical signal, and there is no additional transition structure at the connection point.

[0042] Subwavelength grating structures 21 are located at the output end of the input waveguide 22a and the input end of the output waveguide 22b, respectively. Specifically, a first subwavelength grating structure 21 is set at the output end of the input waveguide 22a, and a second subwavelength grating structure 21 is set at the input end of the output waveguide 22b. The first subwavelength grating structure 21 and the second subwavelength grating structure 21 are symmetrically distributed about the center of the curved waveguide 23 to ensure the mode consistency of the optical signal in the entire transmission path.

[0043] The subwavelength grating structure 21 is composed of multiple substructures. Its core function is to match the optical propagation mode of the straight waveguide section with the optical propagation mode of the curved waveguide section 23 by controlling the optical field distribution, thereby reducing the mode mismatch loss between the two and suppressing the optical field radiation leakage caused by the waveguide bending. This enables low-loss transmission of optical signals during the 90° turn transmission process and is used to match the optical propagation modes of the straight waveguide section and the curved waveguide section 23.

[0044] As an optional embodiment, the substructure of the subwavelength grating structure 21 is an isosceles triangle. This shape selection is not randomly set, but is based on the optical field control requirements and the refractive index distribution law. The symmetrical structure of the isosceles triangle can form a uniform and continuous stepped refractive index distribution in the waveguide width direction, providing guidance for the optical signal and avoiding optical field distortion caused by structural asymmetry.

[0045] The base of the isosceles triangle is located inside the waveguide, and the vertex is located outside the waveguide. Since the outer path of the curved waveguide 23 is longer, the light field will naturally shift outward to reduce phase mismatch loss. The isosceles triangle structure with the inner base and the outer vertex can guide the light field of the straight waveguide section to converge to the outside of the waveguide through the gradient change of refractive index, so that the light propagation mode of the straight waveguide matches the light propagation mode of the curved waveguide 23, thereby reducing energy leakage.

[0046] The center-to-center spacing of two adjacent isosceles triangles is N1, and the value of N1 ranges from 0.08 to 0.12 micrometers. In this embodiment, the center-to-center spacing N1 of two adjacent isosceles triangles is set to 0.1 micrometers. If the spacing is too small, it will cause etching residue or structural adhesion of adjacent substructures during micro-nano fabrication, affecting optical performance. If the spacing is too large, it will disrupt the continuity of the stepped refractive index, causing discontinuities in the optical field modulation and making it impossible to achieve a smooth mode transition. The spacing of 0.1 micrometers can ensure that a continuous refractive index gradient is formed between substructures, guiding the optical field to turn smoothly.

[0047] The distance between the isosceles triangle closest to the output end of the input waveguide 22a or the input end of the output waveguide 22b and the corresponding waveguide end is N2. The value of N2 ranges from 0.08 to 0.12 micrometers. In this embodiment, N2 is set to 0.1 micrometers. If the distance is too small, it may cause the substructure to overlap with the main body of the waveguide, destroying the original mode of the waveguide. The distance of 0.1 micrometers can ensure that the optical signal smoothly transitions from the straight waveguide through the subwavelength grating structure 21 to the curved waveguide 23, and then smoothly transitions from the curved waveguide 23 through the other side of the subwavelength grating structure 21 to the output waveguide 22b, without any sudden changes in the optical field throughout the process, reducing the loss at the junction.

[0048] As an optional embodiment, the base length of the isosceles triangle is 0.1~0.2 micrometers and the height is 1.0~1.5 micrometers; the total number of substructures of the subwavelength grating structure 21 is 15~30.

[0049] In this embodiment, the bottom edge length is precisely set to 0.1754 micrometers, and the height is precisely set to 1.2 micrometers. The substructure size is less than 1 / 4 to 1 / 2 of the wavelength of light, which can avoid additional diffraction loss of light signal during transmission and ensure that the subwavelength structure can give full play to the step refractive index modulation effect.

[0050] The total number of substructures in the subwavelength grating structure 21 is set to 23. This number is the optimal value verified through multiple sets of comparative experiments. Please refer to the appendix. Figure 7 When the total number of substructures of the subwavelength grating structure 21 is set to 23, the transmittance reaches its maximum value.

[0051] As an optional embodiment, the phase change material of the subwavelength grating structure 21 is an amorphous structure b2, and the phase change material of the bus waveguide 22 and the bent waveguide 23 is a crystalline structure b1.

[0052] The core function of the subwavelength grating structure 21 is to achieve mode matching between the straight waveguide section and the curved waveguide section 23. It adopts amorphous Sb2Se3, which forms a significant refractive index gradient with the crystalline waveguide, and can construct a stepped refractive index field to actively guide the light field of the straight waveguide section to gradually shift to the outside of the waveguide.

[0053] Bus waveguide 22 and curved waveguide 23 serve as the main channels for optical signal transmission, and their core requirement is strong optical field confinement capability. The higher refractive index of crystalline Sb2Se3 can create a stronger optical field confinement effect, making the energy flow of the optical signal more concentrated inside the waveguide and effectively reducing the leakage of the optical field to the substrate or external environment.

[0054] As an optional embodiment, the width of the bus waveguide 22 and the curved waveguide 23 is 1.0~1.5 micrometers, the length along the waveguide extension direction is 8~12 micrometers, and the thickness is 80~120 nanometers; the thickness of the phase change material layer of the subwavelength grating structure 21 is 80~120 nanometers. In this embodiment, the width of the bus waveguide 22 and the curved waveguide 23 is uniformly set to 1.2 micrometers, the length along the extension direction of the input waveguide 22a and the output waveguide 22b is set to 10 micrometers, and the thickness of the bus waveguide 22 and the curved waveguide 23 is the same as the thickness of the Sb2Se3 phase change material layer of the device layer, which is 100 nanometers.

[0055] As an optional embodiment, the substrate layer includes a first dielectric layer b4 and a second dielectric layer b3, with the second dielectric layer b3 located above the first dielectric layer b4; the first dielectric layer b4 is a silicon dioxide layer with a thickness of 1.5 to 2.5 micrometers; and the second dielectric layer b3 is a silicon nitride layer with a thickness of 250 to 350 nanometers.

[0056] The substrate layer adopts a double-layer stacked structure of a first dielectric layer b4 and a second dielectric layer b3, wherein the second dielectric layer b3 is closely attached to the upper surface of the first dielectric layer b4 to form a stable composite substrate. The first dielectric layer b4 is specifically made of silicon dioxide, and in this embodiment, it is 2 micrometers thick. The second dielectric layer b3 is made of silicon nitride and is closely disposed on the first dielectric layer b4, and in this embodiment, it is 300 nanometers thick. The low refractive index of the silicon dioxide layer and the medium refractive index of the silicon nitride layer work together to form an optical isolation barrier, so that the energy flow of the optical signal is mainly concentrated inside the device layer.

[0057] As an optional embodiment, the curved waveguide 23 is a circular arc curved structure with a bending radius of 4.5~5.5 micrometers. The bending radius of the outer waveguide wall of the curved waveguide 23 is larger than that of the inner waveguide wall. In this embodiment, the curved waveguide is a conventional circular arc curved structure with a radius of 5 micrometers and a waveguide width of 1.2 micrometers; the bending radius of the outer waveguide wall is 5.6 micrometers, and the bending radius of the inner waveguide wall is 4.4 micrometers. The input and output ends of the curved waveguide 23 segment are directly connected by conventional straight waveguides. The subwavelength structure utilizes the stepped refractive index to guide light to propagate closer to the outer waveguide wall, consistent with the light propagation mode in the curved waveguide 23, thus reducing mode matching loss.

[0058] The present invention also proposes a power adjustment method for the above-mentioned curved waveguide 23 based on optical phase change material: by adjusting the number of substructures of the subwavelength grating structure 21, the coupling degree of the optical propagation mode between the straight waveguide segment and the curved waveguide 23 segment is changed, thereby controlling the output optical power;

[0059] Specifically, power regulation is achieved by adjusting the number of effective substructures in the subwavelength grating structure 21, thereby changing the coupling degree of the optical propagation modes between the straight waveguide segment and the curved waveguide segment 23, and thus controlling the output optical power. As the core component of mode matching, the number of subwavelength grating structures directly determines the integrity and continuity of the stepped refractive index distribution.

[0060] When the number of substructures is sufficient, the refractive index gradient is continuous and gentle, which can guide the straight waveguide optical field to deflect to the outside of the waveguide to the maximum extent. It is highly compatible with the optical propagation mode of the curved waveguide 23, and the mode coupling efficiency is the highest. The output optical power, i.e., the transmittance, reaches its peak. As the number of substructures decreases, the continuity of the refractive index gradient is disrupted, the mode guiding effect weakens, the mode mismatch loss between the straight waveguide and the curved waveguide 23 increases, the optical field radiation leakage intensifies, and the output optical power decreases steadily, thus forming a complete power adjustment range.

[0061] The number of substructures can be adjusted from N to 0, where N is an integer from 15 to 30.

[0062] This embodiment preferentially uses the optimal value N=23, that is, the adjustment range is 23~0. This range has been verified by multiple sets of experiments: as shown in the attached figure. Figure 7 As shown, when the number of substructures exceeds 23 or 30, the effect of improving transmittance tends to plateau and gradually deteriorates. Adding additional substructures cannot significantly improve output power, but will instead increase the difficulty of control and process cost.

[0063] When the number of substructures is less than 15, the mode matching effect drops sharply, the transmittance is below 0.7, and the adjustment accuracy deteriorates, failing to meet the power control requirements. Based on the test data, the power adjustment range corresponding to this adjustment range is 0.86~0.65. When the number of substructures is 23, the transmittance of the 1550 nm light signal reaches 0.86. As the number of substructures gradually decreases to 0, the transmittance drops to 0.65. The linear segment is located in the range of 20 to 3 substructures. Within this segment, for every substructure reduced, the average transmittance adjustment step is approximately 0.01, exhibiting high adjustment accuracy and good linearity, enabling precise power calibration.

[0064] The nonlinear section is divided into two segments: 23 to 21 substructures and 2 to 0 substructures. The average transmittance adjustment step size of the nonlinear section is about 0.003, and the power change is gradual, which can be used for fine-tuning of small power.

[0065] The method for adjusting the number of substructures is as follows: from the input end near the input waveguide 22a or the output end near the output waveguide 22b, the substructures of the subwavelength grating structure 21 are sequentially erased or written using pulsed lasers towards the bend waveguide 23; the number of substructures of the subwavelength grating structure 21 on the input waveguide 22a side and the output waveguide 22b side is adjusted synchronously.

[0066] Under the same experimental conditions, a comparative experiment was conducted on the curved waveguide of this invention with a radius of 5 micrometers, and on conventional circular arc curved waveguides, Euler curved waveguides, and fifth-order Bessel curved waveguides. The experimental data of the measured transmittance are shown in the table below:

[0067] The bending structure has a radius of 5 micrometers. transmittance Conventional circular arc bending 0.65 Euler bending 0.49 Fifth-order Bezier bend 0.32 Structure of the present invention 0.87

[0068] Compared with existing technologies, the power regulation scheme of the present invention does not require additional regulation components such as attenuators and modulators. It directly utilizes the subwavelength grating structure 21 of the bent waveguide 23 itself and the phase change material characteristics to achieve functional integration, which simplifies the chip structure, reduces integration complexity, and avoids additional losses introduced by additional components, thus meeting the development needs of integrated photonics.

[0069] The present invention also proposes a method for fabricating a bent waveguide 23 based on optical phase change material as described above, comprising the following steps:

[0070] A phase change material layer is deposited on the surface of the second dielectric layer b3 of the substrate by magnetron sputtering. The initial state of the phase change material layer is amorphous.

[0071] An antioxidant protective layer is deposited on the surface of the phase change material layer;

[0072] Figure 2 In this context, b1 represents the crystalline state of the phase change material, and b2 represents the amorphous state of the phase change material.

[0073] Pulsed lasers are used to write the crystalline input waveguide 22a, the bent waveguide 23, and the output waveguide 22b.

[0074] Amorphous subwavelength grating structures 21 are written using pulsed lasers at the output end of the input waveguide 22a and the input end of the output waveguide 22b.

[0075] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A bent waveguide based on optical phase change materials, characterized in that: Includes substrate layer and device layer; The device layer is disposed on the substrate layer; The device layer includes a subwavelength grating structure (21), a bus waveguide (22), and a bent waveguide (23). The bus waveguide (22) includes an input waveguide (22a) and an output waveguide (22b). The output end of the input waveguide (22a) is connected to the input end of the curved waveguide (23), and the output end of the curved waveguide (23) is connected to the input end of the output waveguide (22b). The subwavelength grating structure (21) is located at the output end of the input waveguide (22a) and the input end of the output waveguide (22b), respectively. The subwavelength grating structure (21) is composed of multiple substructures and is used to match the optical propagation modes of the straight waveguide segment and the curved waveguide (23) segment.

2. The bent waveguide based on optical phase change material according to claim 1, characterized in that: The substructure of the subwavelength grating structure (21) is an isosceles triangle, with the base of the isosceles triangle located inside the waveguide and the vertex located outside the waveguide. The center-to-center distance between two adjacent isosceles triangles is N1, and the value of N1 ranges from 0.08 to 0.12 micrometers. The distance between the isosceles triangle closest to the output end of the input waveguide (22a) or the input end of the output waveguide (22b) and the corresponding waveguide end is N2, and the value of N2 ranges from 0.08 to 0.12 micrometers.

3. The bent waveguide based on optical phase change material according to claim 2, characterized in that: The isosceles triangle has a base length of 0.1 to 0.2 micrometers and a height of 1.0 to 1.5 micrometers; the subwavelength grating structure (21) has a total of 15 to 30 substructures.

4. The bent waveguide based on optical phase change material according to claim 1, characterized in that: The phase change material of the subwavelength grating structure (21) is an amorphous structure (b2), while the phase change materials of the bus waveguide (22) and the curved waveguide (23) are crystalline structures (b1).

5. The bent waveguide based on optical phase change material according to claim 1, characterized in that: The width of the bus waveguide (22) and the curved waveguide (23) is 1.0~1.5 micrometers, the length along the waveguide extension direction is 8~12 micrometers, and the thickness is 80~120 nanometers; the phase change material layer of the subwavelength grating structure (21) has a thickness of 80~120 nanometers.

6. The bent waveguide based on optical phase change material according to claim 1, characterized in that: The substrate layer includes a first dielectric layer (b4) and a second dielectric layer (b3), with the second dielectric layer (b3) located on top of the first dielectric layer (b4); the first dielectric layer (b4) is a silicon dioxide layer with a thickness of 1.5 to 2.5 micrometers; the second dielectric layer (b3) is a silicon nitride layer with a thickness of 250 to 350 nanometers.

7. The bent waveguide based on optical phase change material according to claim 1, characterized in that: The curved waveguide (23) is a circular arc curved structure with a bending radius of 4.5~5.5 micrometers; the bending radius of the outer waveguide wall of the curved waveguide (23) is larger than that of the inner waveguide wall.

8. A power regulation method for a bent waveguide based on optical phase change materials as described in any one of claims 1 to 7, characterized in that: By adjusting the number of substructures in the subwavelength grating structure (21), the coupling degree of the optical propagation mode between the straight waveguide segment and the curved waveguide (23) segment is changed, thereby controlling the output optical power; The number of substructures can be adjusted from N to 0, where N is an integer from 15 to 30.

9. The power regulation method according to claim 8, characterized in that: The method for controlling the number of substructures is as follows: from the input end near the input waveguide (22a) or the output end near the output waveguide (22b), the substructures of the subwavelength grating structure (21) are erased or written sequentially in the direction near the curved waveguide (23); The number of subwavelength grating structure (21) substructures on the input waveguide (22a) side and the output waveguide (22b) side is adjusted synchronously.

10. A method for fabricating a bent waveguide based on an optical phase change material as described in any one of claims 1 to 7, characterized in that: A phase change material layer is deposited on the surface of the second dielectric layer (b3) of the substrate by magnetron sputtering, wherein the initial state of the phase change material layer is amorphous. An antioxidant protective layer is deposited on the surface of the phase change material layer; Pulsed lasers were used to write the crystalline input waveguide (22a), the bent waveguide (23), and the output waveguide (22b). Amorphous subwavelength grating structures (21) are written using pulsed lasers at the output end of the input waveguide (22a) and the input end of the output waveguide (22b).

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