A planar lightwave circuit tunable optical splitter based on phase change material and a dynamic adjustment method

Abstract

A kind of planar optical waveguide adjustable optical brancher based on phase change material and dynamic adjustment method, belong to integrated photonics and optical communication field, it includes 1 × 2 Y type branch structure, Mach-Zehnder interferometer structure, directional coupler structure, each optical structure surface adds cover layer, each optical structure surface uses same method to handle: deposition SiO2 Lower cladding layer as bottom structure;SiO2 Lower cladding layer surface deposition ridge-shaped SiO2 Core layer, deposition SiO2 Upper cladding layer completes three-layer stack;And Mach-Zehnder interferometer structure and directional coupler structure area, its SiO2 Upper cladding layer surface successively deposits amorphous Sb2S3 phase change layer and Al2O3 Protective layer;And by laser selected area induction Mach-Zehnder interferometer structure right interference arm and the Sb2S3 layer phase transition of directional coupler structure right arm area connected with it form laser-induced crystalline Sb2S3 functional layer.The planar optical waveguide adjustable optical brancher designed by the application has the advantages of zero static power consumption, dynamic reconfigurable and strong process compatibility.

Description

Technical Field

[0001] The present invention belongs to the field of integrated photonics and optical communications, and relates to a planar optical waveguide tunable optical splitter based on phase change materials and a dynamic adjustment method. The present invention is suitable for situations where high flexibility in optical power distribution and low power consumption are required in new generation optical communication systems such as intelligent optical networks and passive optical networks (PONs). Background Art

[0002] Optical routers are core functional units in modern fiber-optic communication networks, particularly passive optical networks (PONs), responsible for efficient and flexible allocation of optical signal transmission paths. Since their commercialization in the 1990s, traditional planar lightwave circuit (PLC) optical splitters, based on fixed splitting ratios, have been widely used in various optical router construction components due to their low cost, high reliability, and excellent integration. However, with the rapid growth of network traffic, the increasing diversification of service types, and the increasing demand for network flexibility and intelligent management, fixed optical routers based on fixed splitters face the dual limitations of rigid functionality and a lack of dynamic control capabilities. Their fixed splitting ratio (e.g., 50:50) cannot be changed after device manufacturing, making them difficult to adapt to network expansion, service adjustments, and fault recovery requirements. Frequent device replacements not only cause service interruptions but also increase operational and maintenance costs and waste resources. Furthermore, these routers cannot dynamically adjust optical power allocation strategies based on real-time traffic, user priorities, or network status, severely limiting network resource utilization and overall system performance.

[0003] Therefore, developing optical router technology with tunable splitting ratios has become a key direction for building the next generation of intelligent, efficient optical networks. To overcome the fixed splitting ratio limitations of traditional optical routers, researchers have proposed tunable optical routers based on the thermo-optic effect. These employ microheaters to manipulate the waveguide refractive index, enabling dynamic adjustment of the splitting ratio [Chinese Invention Patent 200710066839.5]. However, these mainstream technologies still face significant bottlenecks. First, they suffer from high power consumption and poor non-volatility. Thermo-optical control requires continuous power to maintain its state; a power outage causes the set splitting ratio to be lost, requiring repeated energy configuration, severely limiting its feasibility in large-scale applications such as PONs, where low power consumption is critical. Second, the manufacturing process is complex and costly. The integration of microheaters requires multiple photolithography, etching, and electrode fabrication steps beyond the standard PLC process, significantly increasing manufacturing complexity and cost, contradicting the original design principle of PLC technology: low cost and high integration.

[0004] Phase change materials (PCMs) offer a novel technological approach to overcome the high energy consumption and complex manufacturing processes inherent in thermo-optical tunable optical routers. PCMs, such as chalcogenides, enable rapid, reversible, and nonvolatile phase transitions between amorphous and crystalline states, effectively maintaining their optical state for extended periods without the need for continuous power supply. This effectively addresses the high static power consumption of thermo-optical control devices. Although early phase change materials, such as Ge2Sb2Te5 (GST), exhibited high optical losses in communication wavelengths (e.g., 1550nm), limiting their application in low-loss photonic devices, the recent emergence of new low-loss materials, such as Sb2S3, has opened new opportunities for realizing low-power, high-performance tunable photonic devices. Sb2S3 has a wide transparency window (covering the visible to near-infrared band), high refractive index contrast (Δn≈0.6), extremely low optical loss (k<0.0001 in the 1550nm band), excellent thermal stability and maskless processing capabilities compatible with laser direct writing, which can significantly simplify the manufacturing process and reduce costs. This type of PCMs can provide technical feasibility and breakthroughs for the formation of a low-energy tunable optical splitter. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a planar optical waveguide tunable optical splitter based on phase change material and a dynamic adjustment method. Specifically, the present invention is based on the traditional silica planar optical waveguide structure, innovatively integrating the Sb2S3 phase change functional layer and the Al2O3 protective layer to form a dynamic tunable optical splitter with a simple structure, low loss, and non-volatility, and a method for regulating and controlling the same. The present invention achieves dynamic reconstruction of the splitting ratio through laser selectively induced phase change, which can effectively overcome the problems existing in the prior art such as high static power consumption, unadjustable splitting ratio, and complex manufacturing process. The designed planar optical waveguide tunable optical splitter has the advantages of zero static power consumption, dynamic reconfigurability, and strong process compatibility.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A phase-change material-based planar waveguide tunable optical splitter is constructed on a standard PLC platform and consists of three cascaded optical structures. This is an improved planar waveguide tunable optical splitter with an integrated multilayer structure based on a traditional silica planar waveguide structure. Since traditional silica planar waveguide structures include a 1×2 Y-type branching structure, a Mach-Zehnder interferometer structure, and a directional coupler structure, the planar waveguide tunable optical splitter designed in the present invention also consists of a 1×2 Y-type branching structure, a Mach-Zehnder interferometer structure, and a directional coupler structure, with a covering layer added to the surface of each structure.

[0008] The surface of the 1x2 Y-type branch structure, the Mach-Zehnder interferometer structure and the directional coupler structure is treated by the same method: first, a SiO2 lower cladding layer is formed as a bottom structure by chemical vapor deposition; then, a SiO2 core layer material is deposited on the surface of the SiO2 lower cladding layer, and a ridge-shaped SiO2 core layer with a square cross-section is processed by ultraviolet lithography and reactive ion etching; finally, a SiO2 upper cladding layer is deposited to complete the three-layer stack. In particular, in the Mach-Zehnder interferometer structure and the directional coupler structure region, the surface of the SiO2 upper cladding layer needs to be sequentially deposited with an amorphous Sb2S3 phase change layer and an Al2O3 protective layer; and the amorphous Sb2S3 phase change layer in the right interference arm of the Mach-Zehnder interferometer structure and the right arm region of the directional coupler structure connected with the right interference arm is phase-changed by laser selective induction, realizing local conversion from amorphous state to crystalline state and forming a laser-induced crystalline Sb2S3 phase change layer.

[0009] Each part is as follows:

[0010] The 1x2 Y-type branch structure as an input end is used to divide or distribute the input optical signal to two outputs according to the initial design ratio, and is transmitted to the left and right interference arms of the Mach-Zehnder interferometer structure. The covering layer on the surface of the 1x2 Y-type branch structure is composed of a branch structure SiO2 lower cladding layer, a branch structure SiO2 core layer and a branch structure SiO2 upper cladding layer, wherein the branch structure SiO2 lower cladding layer is a bottom structure, the branch structure SiO2 core layer is a strip structure, and the branch structure SiO2 upper cladding layer is an upper structure. Specifically, the bottom structure is deposited on the surface of the 1x2 Y-type branch structure by chemical vapor deposition; the strip structure is prepared on the SiO2 lower cladding layer by chemical vapor deposition, lithography and etching, and the branch structure SiO2 core layer is a strip-shaped ridge waveguide on the SiO2 lower cladding layer, with a cross-sectional size of 6 μm x 6 μm, forming an optical transmission channel; and the SiO2 upper cladding layer is deposited on the SiO2 lower cladding layer and the SiO2 core layer by chemical vapor deposition.

[0011] The Mach-Zehnder interferometer structure is composed of two parallel interference arms, namely the left interference arm and the right interference arm. The covering layer on the surface of the Mach-Zehnder interferometer structure is composed of a Mach-Zehnder interferometer structure SiO2 lower cladding layer, a Mach-Zehnder interferometer structure SiO2 core layer, and a Mach-Zehnder interferometer structure SiO2 upper cladding layer; and the surface of the Mach-Zehnder interferometer structure SiO2 upper cladding layer of the left interference arm is processed in sequence with a Mach-Zehnder interferometer structure amorphous Sb2S3 phase change layer and a Mach-Zehnder interferometer structure Al2O3 protective layer, and the surface of the Mach-Zehnder interferometer structure SiO2 upper cladding layer of the right interference arm is processed with a Mach-Zehnder interferometer structure. The laser-induced crystalline Sb2S3 phase-change layer and the Mach-Zehnder interferometer structure's Al2O3 protective layer are combined. The Mach-Zehnder interferometer structure's SiO2 lower cladding layer forms the bottom layer, the Mach-Zehnder interferometer structure's SiO2 core layer is a stripe-shaped structure, and the Mach-Zehnder interferometer structure's SiO2 upper cladding layer forms the top layer. Both the Mach-Zehnder interferometer structure's amorphous Sb2S3 phase-change layer and the Mach-Zehnder interferometer structure's laser-induced crystalline Sb2S3 phase-change layer are modulation structures, with the Mach-Zehnder interferometer structure's Al2O3 protective layer serving as the top protective layer. Lasers are used to control the refractive index of the Sb2S3 phase-change layer in the modulation structure above the right interferometer arm, thereby altering the interference phase of the output light and adjusting the splitting ratio of the output light from the left and right interferometer arms. Specifically: the processing method of the Mach-Zehnder interferometer structure SiO2 lower cladding, Mach-Zehnder interferometer structure SiO2 core layer, and Mach-Zehnder interferometer structure SiO2 upper cladding is the same as that of the branch structure SiO2 lower cladding, branch structure SiO2 core layer, and branch structure SiO2 upper cladding in the 1×2Y branch structure; the amorphous Sb2S3 phase change layer of the Mach-Zehnder interferometer structure and the Al2O3 protective layer of the Mach-Zehnder interferometer structure are prepared in sequence by magnetron sputtering deposition, and then the laser direct writing method is used to position the laser spot above the right interference arm of the Mach-Zehnder interferometer structure for processing to obtain a laser-induced crystalline Sb2S3 phase change layer.

[0012] The core function of the directional coupler structure is to couple the optical signals output by the left and right interferometer arms of the Mach-Zehnder interferometer structure, thereby regulating the optical signal distribution ratio, i.e., the splitting ratio. Its efficiency depends on the directional coupler structure design and the properties of the Sb2S3 phase-change material. The covering layer on the surface of the directional coupler structure consists of a SiO2 lower cladding layer of the directional coupler structure, a SiO2 core layer of the directional coupler structure, and a SiO2 upper cladding layer of the directional coupler structure; and an amorphous Sb2S3 phase change layer of the directional coupler structure and an Al2O3 protective layer of the directional coupler structure are sequentially processed on the surface of the SiO2 upper cladding layer of the directional coupler structure connected to the left interference arm, and a laser-induced crystalline Sb2S3 phase change layer of the directional coupler structure and an Al2O3 protective layer of the directional coupler structure are processed on the surface of the SiO2 upper cladding layer of the directional coupler structure connected to the right interference arm; wherein the SiO2 lower cladding layer of the directional coupler structure is a bottom structure, the SiO2 core layer of the directional coupler structure is a strip structure, the SiO2 upper cladding layer of the directional coupler structure is an upper structure, the amorphous Sb2S3 phase change layer of the directional coupler structure and the laser-induced crystalline Sb2S3 phase change layer of the directional coupler structure are both modulation structures, and the Al2O3 protective layer of the directional coupler structure is a top protective layer. Laser modulation is used to control the refractive index of the Sb2S3 phase-change layer in the directional coupler structure, further regulating the coupling coefficient of the output light between the left and right interferometer arms in the Mach-Zehnder interferometer structure, thereby expanding the adjustment range of the splitting ratio. Specifically, the SiO2 lower cladding layer, SiO2 core layer, and SiO2 upper cladding layer of the directional coupler structure are processed in the same manner as the branched structure SiO2 lower cladding, SiO2 core layer, and SiO2 upper cladding in the 1×2Y-branched structure. The Al2O3 protective layers of the modulation structure and directional coupler structure are processed in the same manner as their counterparts in the Mach-Zehnder interferometer structure.

[0013] Furthermore, the parameters of the laser are: wavelength 532nm, power 5mW, and scanning speed 10μm / s.

[0014] A method for dynamically adjusting a planar optical waveguide tunable optical splitter based on phase change material comprises the following steps:

[0015] In the first step, the laser-induced directional crystallization of the laser-induced crystalline Sb2S3 phase change layer of the Mach-Zehnder interferometer structure on the surface of the right interferometer arm of the Mach-Zehnder interferometer structure is performed. Specifically:

[0016] In step 1.1, a 532 nm continuous laser with a spot size of 2 μm is used to scan the upper surface of the right interferometer arm in the Mach-Zehnder interferometer structure. The laser power is set to 5 mW and the direct writing speed is set to 10 μm / s, so that the Sb2S3 phase change material in the amorphous Sb2S3 phase change layer of the Mach-Zehnder interferometer structure undergoes a phase change, thereby forming uniform and directional crystalline stripes on the surface of the laser-induced crystalline Sb2S3 phase change layer (i.e., Sb2S3 thin film) of the Mach-Zehnder interferometer structure of the right interferometer arm.

[0017] Step 2: Control the splitting ratio of the output light from the Mach-Zehnder interferometer structure after laser-induced phase change. Specifically:

[0018] In step 2.1, build a loss measurement platform consisting of a 1550nm continuous laser light source with a power of 3mW-10mW, a lensed optical fiber with a core diameter of 8-10μm, a planar optical waveguide tunable optical splitter, a ×10 collection objective lens, and an infrared camera with a wavelength range of 750nm-2.5μm.

[0019] In step 2.2, place the planar waveguide tunable optical splitter in the center of the three-axis translation stage. Turn on the 1550 nm continuous laser light source and set the power to 5 mW. Adjust the lens fiber position so that the input light is coupled into the planar waveguide tunable optical splitter and the power meter reads the maximum value. Record the output optical power reading on the power meter.

[0020] In step 2.3, a 1550 nm laser is input. After passing through the 1×2 Y-branch structure, the Mach-Zehnder interferometer structure without laser-induced phase change, and the directional coupler structure without laser-induced phase change, the measured output light has a splitting ratio of 50:50, which is set as the initial state.

[0021] In step 2.4, a laser with a power of 5 mW, a scanning speed of 10 μm / s, and a wavelength of 532 nm was used to induce a phase change in the phase-change material Sb2S3 within the modulation structure on the left interferometer arm of the MZI structure. Uniform and directional crystalline stripes were formed on the surface. The length of the crystalline region of the Sb2S3 phase-change material was controlled by the laser scanning area. On the right interferometer arm of the MZI structure, a selective phase change was performed on the amorphous Sb2S3 phase-change layer and the Al2O3 protective layer covering the MZI structure. The laser action path was from the Al2O3 protective layer through the amorphous Sb2S3 phase-change layer of the MZI structure, focusing on the interface of the laser-induced crystalline Sb2S3 phase-change layer of the MZI structure. The direct writing area is controlled to scan along the axial direction of the right interferometer arm waveguide to form continuous crystallization stripes. The length of the stripes is the straight-line distance from the starting end to the ending end. The length increases from 1mm to 6mm with a step size of 1mm.

[0022] In step 2.5, input a 1550nm laser and record the splitting ratio of the output light when the laser-induced crystalline Sb2S3 phase change layer of the Mach-Zehnder interferometer structure and the laser-induced crystalline Sb2S3 phase change layer of the directional coupler structure undergo phase change (different crystalline region lengths) in real time when passing through the 1×2Y-branch structure, the Mach-Zehnder interferometer structure with laser-induced phase change in step 2.4, and the directional coupler structure without laser-induced phase change.

[0023] In step 2.6, according to experimental records, when a 1550nm laser is input, after passing through a 1×2Y-branched structure, a Mach-Zehnder interferometer structure with laser-induced phase change, and a directional coupler structure without laser-induced phase change, the maximum controllable splitting ratio of the output light is 80:20.

[0024] Step 3: Optimize the output light splitting ratio range of the directional coupler structure. Specifically:

[0025] In step 3.1, on the surface of one arm of the directional coupler structure, the phase change material Sb2S3 in its modulation structure is induced by laser to undergo phase change, and the length of the crystallization region of the phase change material Sb2S3 is controlled to increase from 1 mm to 2 mm by using the laser scanning area.

[0026] In step 3.2, when 1550nm light is input and passes through the 1×2Y-branch structure, the Mach-Zehnder interferometer structure for laser-induced phase change, and the directional coupler structure for laser-induced phase change, the splitting ratio of the output light during the phase change of the laser-induced phase change material Sb2S3 is recorded in real time. The maximum control range of the splitting ratio is expanded from 80:20 to 99:1.

[0027] Compared with the existing tunable optical router technology based on thermo-optical effect, the present invention has the following advantages:

[0028] (1) Zero static power consumption and non-volatility: The lattice structure based on the phase change material Sb2S3 is highly stable in the absence of an external electric field, achieving non-volatile retention of the optical state. The Sb2S3-based planar optical waveguide tunable optical splitter constructed in this study can maintain the set state for a long time without continuous power supply after the splitting ratio is adjusted, significantly reducing static power consumption and having the low energy consumption advantage of "write once, maintain long-term".

[0029] (2) Ultra-low optical loss: By optimizing the purity control and precise element ratio of the Sb2S3 material, it exhibits a significant refractive index contrast (Δn ≥ 0.6) and extremely low optical absorption (extinction coefficient k < 0.0001) before and after the phase transition. Thanks to this material property, the constructed planar optical waveguide tunable optical splitter introduces less than 1dB of transmission loss after the phase transition, achieving high-efficiency, low-loss optical signal control.

[0030] (3) Maskless manufacturing advantages: This invention proposes the use of magnetron sputtering deposition technology to deposit Sb2S3 thin films, combined with direct-write laser processing technology, eliminating the need for traditional photolithography and etching steps, greatly simplifying the preparation process and significantly reducing manufacturing costs. This maskless method has good scalability, is suitable for large-scale production, and can be integrated with existing planar optical waveguide processes, providing a flexible and compatible solution for the manufacture of efficient photonic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of a planar optical waveguide tunable optical splitter;

[0032] Figure 2 1 is a cross-sectional view of various parts of a planar optical waveguide tunable optical splitter; Figure 2 (a) is a 1×2Y-type branch structure along Figure 1 The cross-section view in the AA1 direction, Figure 2 (b) is the Mach-Zehnder interferometer structure along Figure 1 Cross-section view in the BB1 ​​direction, Figure 2 (c) is a directional coupler structure along Figure 1 Cross-section view in the CC1 direction.

[0033] Figure 3 Prepare a flow chart for a planar optical waveguide tunable optical splitter;

[0034] Figure 4 Raman spectra at different laser powers.

[0035] Figure 5 It is a loss measurement platform for planar optical waveguide tunable optical splitters;

[0036] Figure 6 Schematic diagram of the experiment for controlling the splitting ratio of the output light of the Mach-Zehnder interferometer structure after laser-induced phase change; Figure 6 (a) is an experimental schematic diagram of the output light splitting ratio after the Mach-Zehnder interferometer structure; Figure 6 (b) is a graph showing the trend of the splitting ratio under different lengths of laser direct writing;

[0037] Figure 7 Schematic diagram of the experiment for optimizing the output light splitting ratio after passing through the directional coupler structure.

[0038] In the figure: 11×2Y-type branch structure; 2 Mach-Zehnder interferometer structure; 3 directional coupler structure; 4 branch structure SiO2 lower cladding; 5 branch structure SiO2 core layer; 6 branch structure SiO2 upper cladding; 7 Mach-Zehnder interferometer structure SiO2 lower cladding; 8 Mach-Zehnder interferometer structure SiO2 core layer; 9 Mach-Zehnder interferometer structure SiO2 upper cladding; 10 Mach-Zehnder interferometer structure amorphous Sb2S3 phase change layer; 11 Mach-Zehnder interferometer structure laser-induced crystalline Sb2S3 phase change layer; 12 Mach-Zehnder interferometer structure: Al2O3 protective layer; 13: directional coupler structure: SiO2 lower cladding layer; 14: directional coupler structure: SiO2 core layer; 15: directional coupler structure: SiO2 upper cladding layer; 16: directional coupler structure: amorphous Sb2S3 phase change layer; 17: directional coupler structure: laser-induced crystalline Sb2S3 phase change layer; 18: directional coupler structure: Al2O3 protective layer; 19: 1550nm continuous laser light source; 20: lens optical fiber; 21: planar optical waveguide tunable optical splitter; 22: collecting objective lens; 23: infrared camera. DETAILED DESCRIPTION

[0039] The present invention is further described below with reference to specific implementation cases.

[0040] This embodiment provides a planar optical waveguide tunable optical splitter based on phase change material. The planar optical waveguide tunable optical splitter is constructed on a standard PLC platform and consists of three cascaded optical structures. It is an improved planar optical waveguide tunable optical splitter with an integrated multilayer structure based on the traditional silica planar optical waveguide structure. Since the traditional silica planar optical waveguide structure includes a 1×2 Y-type branching structure, a Mach-Zehnder interferometer structure, and a directional coupler structure, the planar optical waveguide tunable optical splitter designed in the present invention also consists of three parts: a 1×2 Y-type branching structure 1, a Mach-Zehnder interferometer structure 2, and a directional coupler structure 3. A covering layer is added to the surface of each structure.

[0041] The surfaces of the 1×2 Y-branch structure 1, the Mach-Zehnder interferometer structure 2, and the directional coupler structure 3 are fabricated using the same method: first, a SiO2 lower cladding layer is formed as the underlying structure via chemical vapor deposition. Core material is then deposited on the surface of the lower cladding layer and processed into a square-cross-section ridged SiO2 core layer via ultraviolet lithography and reactive ion etching. Finally, a SiO2 upper cladding layer is deposited to complete the three-layer stack. Specifically, in the Mach-Zehnder interferometer structure 2 and the directional coupler structure 3, an amorphous Sb2S3 phase change layer and an Al2O3 protective layer are sequentially deposited on the surface of the SiO2 upper cladding. Furthermore, laser selectively induces a phase transition in the amorphous Sb2S3 phase change layer in the right interferometer arm of the Mach-Zehnder interferometer structure 2 and the right arm of the connected directional coupler structure 3, achieving a localized transition from amorphous to crystalline, forming a laser-induced crystalline Sb2S3 phase change layer.

[0042] The specific parts are as follows:

[0043] The 1×2 Y-shaped branching structure 1 serves as the input end, dividing the input optical signal equally or distributing it according to the initial design ratio to two output paths, transmitting it to the left and right interferometer arms of the Mach-Zehnder interferometer structure 2. The surface covering layer of the 1×2 Y-shaped branching structure 1 is composed of a branched SiO2 lower cladding layer 4, a branched SiO2 core layer 5, and a branched SiO2 upper cladding layer 6. The branched SiO2 lower cladding layer 4 is the bottom layer, the branched SiO2 core layer 5 is a strip-shaped structure, and the branched SiO2 upper cladding layer 6 is the upper layer. Specifically, a base structure is deposited on the surface of the 1×2 Y-shaped branched structure 1 using chemical vapor deposition. A stripe-shaped structure is formed on the SiO2 lower cladding 4 using chemical vapor deposition, photolithography, and etching. The branched SiO2 core layer 5, a stripe-shaped ridge waveguide with a cross-sectional size of 6μm × 6μm, is located above the SiO2 lower cladding 4, forming an optical transmission channel. A SiO2 upper cladding 6 is deposited above the SiO2 lower cladding 4 and the SiO2 core layer 5 using chemical vapor deposition. The Mach-Zehnder interferometer structure 2 consists of two parallel interferometer arms: a left interferometer arm and a right interferometer arm. The dimensions of each component in this embodiment are as follows: a branched SiO2 lower cladding 4 with a thickness of 3mm, a length of 8mm, and a width of 256μm; a branched SiO2 core layer 5 with a thickness of 6μm, a length of 8mm, and a width of 6μm; and a branched SiO2 upper cladding 6 with a thickness of 4μm, a length of 8mm, and a width of 256μm.

[0044] The covering layer on the surface of the Mach-Zehnder interferometer structure 2 is composed of a Mach-Zehnder interferometer structure SiO2 lower cladding layer 7, a Mach-Zehnder interferometer structure SiO2 core layer 8, and a Mach-Zehnder interferometer structure SiO2 upper cladding layer 9; and the surface of the Mach-Zehnder interferometer structure SiO2 upper cladding layer 9 of the left interferometer arm is processed in sequence with a Mach-Zehnder interferometer structure amorphous Sb2S3 phase change layer 10 and a Mach-Zehnder interferometer structure Al2O3 protective layer 12, and the surface of the Mach-Zehnder interferometer structure SiO2 upper cladding layer 9 of the right interferometer arm is processed with a Mach-Zehnder interferometer structure laser induction layer 12. The conductive crystalline Sb2S3 phase change layer 11 and the Mach-Zehnder interferometer structure Al2O3 protective layer 12; wherein, the Mach-Zehnder interferometer structure SiO2 lower cladding layer 7 is the bottom structure, the Mach-Zehnder interferometer structure SiO2 core layer 8 is a strip structure, the Mach-Zehnder interferometer structure SiO2 upper cladding layer 9 is the upper structure, the Mach-Zehnder interferometer structure amorphous Sb2S3 phase change layer 10 and the Mach-Zehnder interferometer structure laser-induced crystalline Sb2S3 phase change layer 11 are both modulation structures, and the Mach-Zehnder interferometer structure Al2O3 protective layer 12 is the top protective layer. Specifically: the processing method of the Mach-Zehnder interferometer structure SiO2 lower cladding layer 7, the Mach-Zehnder interferometer structure SiO2 core layer 8, and the Mach-Zehnder interferometer structure SiO2 upper cladding layer 9 is the same as that of the branch structure SiO2 lower cladding layer 4, the branch structure SiO2 core layer 5, and the branch structure SiO2 upper cladding layer 6 in the 1×2Y-type branch structure 1; the surface of the SiO2 upper cladding layer 9 of the Mach-Zehnder interferometer structure of the left interferometer arm and the right interferometer arm is prepared by magnetron sputtering deposition method. S3 phase change layer 10 and Mach-Zehnder interferometer structure Al2O3 protective layer 12; the difference is that the Mach-Zehnder interferometer structure amorphous Sb2S3 phase change layer 10 on the surface of the SiO2 upper cladding 9 of the Mach-Zehnder interferometer structure of the right interferometer arm needs to be laser induced to obtain the Mach-Zehnder interferometer structure laser induced crystalline Sb2S3 phase change layer 11; the Mach-Zehnder interferometer structure amorphous Sb2S3 phase change layer 10 and the Mach-Zehnder interferometer structure laser induced crystalline Sb2S3 phase change layer 11 serve as modulation structures.The dimensions of each part in this embodiment are as follows: a Mach-Zehnder interferometer structure SiO2 lower cladding layer 7 with a thickness of 3 mm, a length of 6 mm, and a width of 256 μm; a Mach-Zehnder interferometer structure SiO2 core layer 8 with a thickness of 6 μm, a length of 6 mm, and a width of 6 μm; a Mach-Zehnder interferometer structure SiO2 upper cladding layer 9 with a thickness of 4 μm, a length of 6 mm, and a width of 256 μm; a Mach-Zehnder interferometer structure amorphous Sb2S3 phase change layer 10 with a thickness of 500 nm, a length of 6 mm, and a width of 256 μm; a Mach-Zehnder interferometer structure laser-induced crystalline Sb2S3 phase change layer 11 with a thickness of 500 nm, a length of 6 mm, and a width of 10 μm; and a Mach-Zehnder interferometer structure Al2O3 protective layer 12 with a thickness of 50 nm, a length of 6 mm, and a width of 256 μm. A laser with a wavelength of 532nm, a power of 5mW, and a scanning speed of 10μm / s is used to control the refractive index of the Sb2S3 phase change layer in the modulation structure above the right interferometer arm, thereby changing the interference phase of the output light and adjusting the splitting ratio of the output light of the left and right interferometer arms.

[0045] The directional coupler structure 3 couples the optical signals output by the left and right interferometer arms of the Mach-Zehnder interferometer structure 2, and its coupling efficiency (which in turn affects the final output splitting ratio) can also be regulated by the Sb2S3 phase change state covering it. The covering layer on the surface of the directional coupler structure 3 is composed of a directional coupler structure SiO2 lower cladding layer 13, a directional coupler structure SiO2 core layer 14, and a directional coupler structure SiO2 upper cladding layer 15; and the directional coupler structure amorphous Sb2S3 phase change layer 16 and the directional coupler structure Al2O3 protective layer 18 are processed in sequence on the surface of the directional coupler structure SiO2 upper cladding layer 15 connected to the left interferometer arm, and the directional coupler structure excitation layer 16 is processed on the surface of the directional coupler structure SiO2 upper cladding layer 15 connected to the right interferometer arm. A light-induced crystalline Sb2S3 phase change layer 17 and a directional coupler structure Al2O3 protective layer 18; wherein the directional coupler structure SiO2 lower cladding layer 13 is the bottom structure, the directional coupler structure SiO2 core layer 14 is a strip structure, the directional coupler structure SiO2 upper cladding layer 15 is the upper structure, the directional coupler structure amorphous Sb2S3 phase change layer 16 and the directional coupler structure laser-induced crystalline Sb2S3 phase change layer 17 are both modulation structures, and the directional coupler structure Al2O3 protective layer 18 is the top protective layer. Specifically, the processing methods for the directional coupler structure SiO2 lower cladding layer 13, directional coupler structure SiO2 core layer 14, and directional coupler structure SiO2 upper cladding layer 15 are the same as those for the branch structure SiO2 lower cladding layer 4, branch structure SiO2 core layer 5, and branch structure SiO2 upper cladding layer 6 in the 1×2 Y-type branch structure 1. The processing methods for the modulation structure and directional coupler structure Al2O3 protective layer 18 are the same as those for the corresponding parts in the Mach-Zehnder interferometer structure 2. The dimensions of each component in this embodiment are as follows: a directional coupler structure SiO2 lower cladding layer 13 with a thickness of 3 mm, a length of 2 mm, and a width of 256 μm; a directional coupler structure SiO2 core layer 14 with a thickness of 6 μm, a length of 2 mm, and a width of 6 μm; a directional coupler structure SiO2 upper cladding layer 15 with a thickness of 4 μm, a length of 2 mm, and a width of 256 μm; and a directional coupler structure amorphous Sb2S3 phase with a thickness of 500 nm, a length of 2 mm, and a width of 256 μm. phase change layer 16; a directional coupler structure laser-induced crystalline Sb2S3 phase change layer 17 with a thickness of 500nm, a length of 2mm, and a width of 256μm; an Al2O3 protective layer 18 with a directional coupler structure with a thickness of 50nm, a length of 2mm, and a width of 256μm; the refractive index of the Sb2S3 phase change layer is controlled by a laser with a wavelength of 532nm, a power of 5mW, and a scanning speed of 10μm / s, thereby further controlling the coupling coefficient of the output light of the two arms and expanding the adjustment range of the splitting ratio.

[0046] This embodiment provides a method for dynamically adjusting a planar optical waveguide tunable optical splitter based on a phase change material, comprising the following steps:

[0047] Step 1: Laser-induced directional crystallization is performed on the laser-induced crystalline Sb2S3 phase change layer 11 of the Mach-Zehnder interferometer structure 2 on the right interference arm surface of the planar optical waveguide tunable optical splitter. Specifically:

[0048] Step 1.1, use a 532nm continuous laser with a spot size of 2μm to scan the upper surface of the right interferometer arm in the Mach-Zehnder interferometer structure 2, set the laser power to 5mW, and the direct writing speed to 10μm / s, so that the Sb2S3 phase change material in the Mach-Zehnder interferometer structure 2 undergoes a phase change, and then uniform and directional crystal stripes are formed on the surface of the laser-induced crystalline Sb2S3 phase change layer 11 (i.e., Sb2S3 thin film) of the Mach-Zehnder interferometer structure of the right interferometer arm.

[0049] Step 1.2: Observe the morphology of the crystallized area of ​​the right support arm (grain size, distribution uniformity) using a metallographic microscope, and measure the Sb-S bond bending vibration of crystalline Sb2S3 at 189 cm -1 290cm of SS bond stretching vibration -1 The characteristic peak verifies the realization of directional crystallization of laser-induced phase change material Sb2S3.

[0050] Step 2: Control the splitting ratio of the output light of the Mach-Zehnder interferometer structure 2 after the laser-induced phase change. Specifically:

[0051] Step 2.1: Build a loss measurement platform consisting of a 1550nm continuous laser light source 19 with a power of 3mW-10mW, a lens fiber 20 with a core diameter of 8-10μm, a planar optical waveguide tunable optical splitter 21, a ×10 collection objective lens 22, and an infrared camera 23 with a wavelength range of 750nm-2.5μm, as shown in the following example: Figure 5 shown.

[0052] Step 2.2: Place the planar waveguide tunable optical splitter in the center of the three-axis translation stage, turn on the 1550nm continuous laser light source 19, set the power to 5mW, adjust the position of the lens fiber 20 so that the input light is coupled into the planar waveguide tunable optical splitter 21, and maximize the power meter reading. Record the output optical power reading of the power meter.

[0053] In step 2.3, a 1550 nm laser is input. After passing through the 1×2 Y-branch structure 1, the Mach-Zehnder interferometer structure 2 without laser-induced phase change, and the directional coupler structure 3 without laser-induced phase change, the measured output light has a splitting ratio of 50:50, which is set as the initial state.

[0054] In step 2.4, a laser with a power of 5 mW, a scanning speed of 10 μm / s, and a wavelength of 532 nm was used to induce a phase change in the phase-change material Sb2S3 in the modulation structure on the left interferometer arm of the MZI structure 2. Uniform and directional crystalline stripes were formed on the surface. The length of the crystalline region of the phase-change material Sb2S3 was controlled by the laser scanning area. On the right interferometer arm of the MZI structure 2, a selective phase change was performed on the amorphous Sb2S3 phase-change layer 10 and the Al2O3 protective layer 12 of the MZI structure. The laser action path was from the Al2O3 protective layer 12 of the MZI structure through the amorphous Sb2S3 phase-change layer 10 of the MZI structure, and was focused at the interface of the laser-induced crystalline Sb2S3 phase-change layer 11 of the MZI structure. The direct writing area is controlled to scan along the axial direction of the right interferometer arm waveguide to form continuous crystallization stripes. The length of the stripes is the straight-line distance from the starting end to the ending end. The length increases from 1mm to 6mm with a step size of 1mm.

[0055] In step 2.5, a 1550 nm laser is input. When the laser passes through the 1×2 Y-branch structure 1, the Mach-Zehnder interferometer structure 2 with laser-induced phase change in step 2.4, and the directional coupler structure 3 without laser-induced phase change, the splitting ratio of the output light is recorded in real time when the laser-induced crystalline Sb2S3 phase change layer 11 of the Mach-Zehnder interferometer structure and the laser-induced crystalline Sb2S3 phase change layer 17 of the directional coupler structure undergo phase change (different crystallization region lengths).

[0056] In step 2.6, according to experimental records, when a 1550nm laser is input, after passing through the 1×2Y-branch structure 1, the Mach-Zehnder interferometer structure with laser-induced phase change 2, and the directional coupler structure without laser-induced phase change 3, the maximum controllable splitting ratio of the output light is 80:20.

[0057] Step 3: Optimize the output light splitting ratio range of the directional coupler structure 3. Specifically:

[0058] In step 3.1, on the surface of one arm of the directional coupler structure 3, the phase change material Sb2S3 in its modulation structure is induced by laser to undergo phase change, and the length of the crystallization region of the phase change material Sb2S3 is controlled to increase from 1 mm to 2 mm by using the laser scanning area.

[0059] In step 3.2, a 1550nm laser is input. When it passes through the 1×2Y-branch structure 1, the laser-induced phase change Mach-Zehnder interferometer structure 2, and the laser-induced phase change directional coupler structure 3, the splitting ratio of the output light during the phase change of the laser-induced phase change material Sb2S3 is recorded in real time. The maximum control range of the splitting ratio is expanded from 80:20 to 99:1.

[0060] This embodiment also provides a method for preparing the aforementioned phase-change material-based planar optical waveguide tunable optical splitter, aiming to construct an integrated structure comprising a low-loss silica waveguide core layer and a Sb2S3 functional layer capable of laser-induced phase change. The surfaces of the 1×2 Y-branch structure 1, Mach-Zehnder interferometer structure 2, and directional coupler structure 3 of the planar optical waveguide tunable optical splitter are prepared using the same method: first, a SiO2 lower cladding layer is formed as the underlying structure by chemical vapor deposition; then, SiO2 core layer material is deposited on the surface of the SiO2 lower cladding layer and processed into a square-cross-section ridge-shaped SiO2 core layer via ultraviolet lithography and reactive ion etching; finally, a SiO2 upper cladding layer is deposited to complete the three-layer stack. In particular, in the Mach-Zehnder interferometer structure and directional coupler structure area, the surface of the SiO2 upper cladding layer needs to be deposited in sequence with an amorphous Sb2S3 phase change layer and an Al2O3 protective layer; and the amorphous Sb2S3 phase change layer in the right interferometer arm of the Mach-Zehnder interferometer structure and the right arm area of ​​the directional coupler structure connected to the right interferometer arm is induced by laser selection to undergo phase change, achieving local conversion from amorphous to crystalline, forming a laser-induced crystalline Sb2S3 phase change layer. The process includes the following steps:

[0061] Step 1: Preparation of SiO2 lower cladding layer of 1×2Y-branch structure 1, Mach-Zehnder interferometer structure 2, and directional coupler structure 3.

[0062] In step 1.1, a high-purity SiO2 wafer with a diameter of 100 mm, a size of 4 inches, and a thickness of 3 mm was used as a substrate. The wafer was cleaned in isopropyl alcohol, anhydrous ethanol, and deionized water for 10 minutes respectively by ultrasonic cleaning, and then dried with nitrogen gas for later use.

[0063] In step 1.2, a nitrogen-doped silicon dioxide lower cladding layer is grown on the SiO2 wafer obtained in the previous step using chemical vapor deposition (CVD) technology to obtain a SiO2 lower cladding layer with a thickness of 500 μm and a size of 4 inches.

[0064] Step 2: Verify the refractive index of the SiO2 lower cladding of the 1×2Y-branch structure 1, the Mach-Zehnder interferometer structure 2, and the directional coupler structure.

[0065] Step 2.1: For the refractive index of the SiO2 lower cladding, precise control is used to adjust the flow rate of SiH4, N2O and doping gas NH3 at 5sccm, and the atomic percentage of nitrogen doping concentration is adjusted to 5% to achieve the target refractive index n≈1.515 of the SiO2 lower cladding.

[0066] In step 2.2, the refractive index of the SiO2 lower cladding layer was measured using a spectroscopic ellipsometer in the 1550nm telecommunications band. The measurement parameters were as follows: wavelength range 1200-1700nm (focused on the 1550nm band), incident angles of 65°, 70°, and 75°, and spot size 1×2mm².

[0067] Step 2.3, analyze the test results of the refractive index of the SiO2 lower cladding, and use the Cauchy model to fit and verify that the refractive index of the SiO2 lower cladding is n=1.515 and the extinction coefficient k≤10 -6 Verify that it reaches the target value n≈1.515 and the extinction coefficient is low enough k≈0, confirming that it is a low-loss optical confinement layer that provides bottom-layer optical confinement for the waveguide.

[0068] Step 3: Deposition of SiO2 core layer on top of SiO2 lower cladding layer.

[0069] Step 3.1, use CVD technology to deposit the germanium-doped SiO2 core layer. By adjusting the flow rate of the germanium-doped precursor GeH4 gas at 10 sccm, controlling the germanium doping concentration to 4% atomic percentage, the temperature to 350℃, and the time to 10 min, a core layer is prepared. The material is SiO2, the thickness is 6.0μm, and the size is 6.0μm×6.0μm.

[0070] Step 4: Perform high temperature annealing and solidification of the SiO2 lower cladding and SiO2 core layer and verify the refractive index.

[0071] Step 4.1: High-temperature annealing is performed to solidify the SiO2 lower cladding layer and SiO2 core layer. The specific parameters are as follows: 1000°C for 4 hours in a nitrogen or oxygen atmosphere. This step aims to eliminate deposition stress, promote film densification, reduce structural defects, and improve material stability and optical quality, laying a solid foundation for subsequent photolithography processes.

[0072] In step 4.2, the refractive index of the SiO2 core layer was tested using an ellipsometer at 1550 nm to verify that the core's refractive index reached the target value of 1.55. The measurement parameters were as follows: wavelength range 1200-1700 nm (focused on the 1550 nm band), incident angles of 65°, 70°, and 75°, and spot size 1 × 2 mm².

[0073] Step 4.3 Analyze the test results of the refractive index of the SiO2 core layer and use the Cauchy model to fit and verify that the refractive index of the SiO2 lower cladding is n=1.55 and the extinction coefficient k≤10 -6Verify that it reaches the target value n≈1.515 and the extinction coefficient is low enough k≈0, confirming that it is an optical transmission layer.

[0074] Step 5: Structural formation of the SiO2 core layer.

[0075] Step 5.1: Apply glue to the SiO2 core layer using a spin coater. Specific coating parameters are as follows: positive-tone AZR6130 photoresist, spin coating speed 3000 rpm for 30 seconds, and a thickness of 1.2 μm. After coating, bake on a hot plate at 100°C for 90 seconds.

[0076] In step 5.2, the photoresist above the SiO2 core layer is exposed using a pre-designed optical mask containing the pattern of the 1×2 Y-branch structure 1, the Mach-Zehnder interferometer structure 2, and the directional coupler structure 3. UV lithography is used to transfer the waveguide pattern onto the photoresist. The specific exposure parameters are as follows: Karl Suss MA6 lithography machine, wavelength 365nm, exposure dose 120mJ / cm². Subsequently, the photoresist above the SiO2 core layer, including the 1×2 Y-branch structure 1, the Mach-Zehnder interferometer structure 2, and the directional coupler structure 3, is developed using the following developer: AZ® 300MIF, development time: 60s. The photoresist in the exposed areas is removed, forming the SiO2 core layer.

[0077] Step 5.3: Etch the SiO2 around the SiO2 core layer using a dry etching process such as reactive ion etching. The etching gas is a mixture of CF4, CHF3, and O2 / Ar. The above photoresist is used as a mask to selectively etch the exposed area. The gas mixture is CF4, CHF3, and O2 / Ar, with a ratio of 5%, an RF power of 60W, and a chamber pressure of 1×10 -6 The etching parameters are precisely controlled using a 5000 mTorr etching time of 5 minutes to ensure the etching depth reaches the bottom of the core layer. The resulting ridge waveguide structure has steep sidewalls, a flat surface with a near 90-degree angle, and a cross-section of 6μm x 6μm. This structure forms the core optical path of the optical waveguide tunable optical splitter and includes a 1×2 Y-branch structure (1), a Mach-Zehnder interferometer (2), and a directional coupler (3).

[0078] In step 5.4, the SiO2 surrounding the SiO2 core layer is debonded and cleaned using O2 plasma ashing at 200W for 10 minutes. Cleaning follows the standard RCA process, thoroughly cleaning the wafer. Step 1: Solvent: NH4OH:H2O2:H2O = 1:1:5, temperature: 75°C, cleaning time: 10 minutes. Step 2: Solvent: HCl:H2O2:H2 = 1:1:6, temperature: 75°C, cleaning time: 10 minutes.

[0079] Step 6: Deposition of cladding layer on SiO2.

[0080] Step 6.1: Deposit a SiO2 upper cladding layer using CVD technology over the etched SiO2 core layer and SiO2 lower cladding layer. The SiO2 upper cladding layer is also made of nitrogen-doped silicon dioxide. CVD process parameters, such as the precursor gas SiH4 flow rate of 20 sccm, N2O flow rate of 500 sccm, and NH3 flow rate of 5 sccm, are precisely controlled to achieve a refractive index n of 1.515 for the SiO2 upper cladding layer. Key control parameters are as follows: deposition rate of 50 nm / min, temperature of 350°C, RF power of 50 W, and deposition time of 80 min. The final thickness of the SiO2 upper cladding layer reaches 4 μm, ensuring that it completely covers the complex waveguide core structure below, including the 1×2 Y-branch structure 1, the Mach-Zehnder interferometer structure 2, and the directional coupler structure 3. It also provides a flat, defect-free surface for the subsequent deposition of functional layers.

[0081] Step 7: Cover the SiO2 with an amorphous Sb2S3 phase change layer and an Al2O3 protective layer.

[0082] Step 7.1: Deposit a functional amorphous Sb2S3 phase change layer on the prepared flat SiO2 upper cladding surface using RF magnetron sputtering technology. The specific sputtering environment is as follows: the chamber background vacuum is 5×10 -6 The sputtering process was carried out at a pressure of 15 mTorr, using 99.999% high-purity argon as the working gas. A 50.8 mm diameter Sb2S3 target with a purity of 99.99% was used. The specific sputtering parameters were as follows: RF power of 80W, working pressure of 15 mTorr, and substrate temperature at room temperature. A uniform, dense, 500 nm thick amorphous Sb2S3 thin film was obtained, serving as the amorphous Sb2S3 phase change layer.

[0083] In step 7.2, an Al2O3 protective layer is deposited on the amorphous Sb2S3 phase change layer using RF magnetron sputtering technology. An Al2O3 target with a purity of 99.99% and a diameter of 50.8 mm is used. The specific sputtering parameters are as follows: RF power of 120 W, operating pressure of 3 mTorr, and deposition rate of approximately 0.0097 nm / s. Finally, a dense Al2O3 layer with a thickness of 50 nm is formed. The main function of this Al2O3 protective layer is to prevent Sb2S3 from oxidizing in subsequent processes or environments; provide mechanical protection and reduce surface damage; and play a certain role in thermal management and heat diffusion during the laser direct writing process.

[0084] Step 7.3: After the deposition is completed, the surface is cleaned by rinsing in an ultrasonic cleaner with isopropyl alcohol, anhydrous ethanol, and deionized water for 10 minutes respectively, and then blown dry with nitrogen to remove surface contaminants.

[0085] In step 7.4, the fabricated device is mounted on a high-precision three-dimensional displacement stage. Laser-induced treatment is performed on the 500nm amorphous Sb2S3 phase-change layer deposited on the right interferometer arm of the Mach-Zehnder interferometer structure 2 and the connected directional coupler structure 3. First, a 532nm continuous laser with a power of 5mW and a 0.45×20 objective lens are used to calibrate the optical path, precisely positioning the laser focus at the starting point of the right interferometer arm of the Mach-Zehnder interferometer structure 2. The three-dimensional displacement stage is then moved along the waveguide axis at a constant scanning speed of 10μm / s, forming continuous crystallized stripes on the surface of the right interferometer arm. The scan is stopped when the target length reaches 1mm. Selective crystallization is performed on the directional coupler structure. After the scan is completed, the completeness of the phase change is verified by in situ Raman spectroscopy. Ultimately, directional crystallized stripes are obtained on the right interferometer arm, and a laser-induced Sb2S3 phase-change layer is obtained on the directional coupler structure. Together, these form a laser-induced crystalline Sb2S3, resulting in the final planar optical waveguide tunable optical splitter.

[0086] The above-described embodiments merely express the implementation methods of the present invention, but should not be understood as limiting the scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A planar optical waveguide tunable optical splitter based on phase change material, characterized in that: The planar optical waveguide tunable optical splitter is composed of three cascaded optical structures, including a 1×2 Y-type branching structure (1), a Mach-Zehnder interferometer structure (2), and a directional coupler structure (3), and a covering layer is added to the surface of each optical structure; The surfaces of the 1×2Y-type branch structure (1), the Mach-Zehnder interferometer structure (2) and the directional coupler structure (3) are processed in the same way: a SiO2 lower cladding layer is formed as the bottom layer structure by chemical vapor deposition; a SiO2 core layer material is deposited on the surface of the SiO2 lower cladding layer, and processed into a ridge-shaped SiO2 core layer with a square cross-section by ultraviolet lithography and reactive ion etching; and finally, a SiO2 upper cladding layer is deposited to complete the three-layer stacking; Furthermore, an amorphous Sb2S3 phase change layer and an Al2O3 protective layer need to be deposited on the surface of the SiO2 upper cladding layer in the Mach-Zehnder interferometer structure (2) and the directional coupler structure (3) in sequence; and the amorphous Sb2S3 phase change layer in the right interferometer arm of the Mach-Zehnder interferometer structure (2) and the right arm region of the directional coupler structure (3) connected to the right interferometer arm undergoes phase change by laser selective induction, thereby realizing local conversion from amorphous state to crystalline state, and forming a laser-induced crystalline Sb2S3 phase change layer.

2. The planar optical waveguide tunable optical splitter based on phase change material according to claim 1, characterized in that: The 1×2Y-type branch structure (1) serves as an input end, and is used to equally divide the input optical signal or distribute it to two outputs according to an initial design ratio, and transmit it to the left interference arm and the right interference arm of the Mach-Zehnder interferometer structure (2); the covering layer on the surface of the 1×2Y-type branch structure (1) is composed of a branch structure SiO2 lower cladding layer (4), a branch structure SiO2 core layer (5), and a branch structure SiO2 upper cladding layer (6).

3. The planar optical waveguide tunable optical splitter based on phase change material according to claim 1, characterized in that: The Mach-Zehnder interferometer structure (2) is composed of a left interferometer arm and a right interferometer arm, and the covering layer on the surface is composed of a Mach-Zehnder interferometer structure SiO2 lower cladding layer (7), a Mach-Zehnder interferometer structure SiO2 core layer (8), and a Mach-Zehnder interferometer structure SiO2 upper cladding layer (9), and a Mach-Zehnder interferometer structure amorphous Sb2S3 phase change layer (10), a Mach-Zehnder interferometer structure Al2O3 phase change layer (11) are sequentially processed on the surface of the Mach-Zehnder interferometer structure SiO2 upper cladding layer (9) of the left interferometer arm by magnetron sputtering deposition. A protective layer (12); a surface of the SiO2 upper cladding layer (9) of the Mach-Zehnder interferometer structure of the right interferometer arm is sequentially processed with a Mach-Zehnder interferometer structure amorphous Sb2S3 phase change layer and a Mach-Zehnder interferometer structure Al2O3 protective layer (12) by magnetron sputtering deposition, and a laser direct writing method is used to position the laser spot on the Mach-Zehnder interferometer structure amorphous Sb2S3 phase change layer of the right interferometer arm of the Mach-Zehnder interferometer structure for processing to obtain a Mach-Zehnder interferometer structure laser-induced crystalline Sb2S3 phase change layer (11); The Mach-Zehnder interferometer structure amorphous Sb2S3 phase change layer (10) and the Mach-Zehnder interferometer structure laser-induced crystalline Sb2S3 phase change layer (11) are both modulation structures; Laser is used to control the refractive index of the Sb2S3 phase change layer in the modulation structure above the right interferometer arm, thereby changing the interference phase of the output light and adjusting the splitting ratio of the output light of the left and right interferometer arms.

4. The planar optical waveguide tunable optical splitter based on phase change material according to claim 1, characterized in that: The directional coupler structure (3) couples the optical signals output by the left interference arm and the right interference arm of the Mach-Zehnder interferometer structure (2) to adjust the optical signal distribution ratio; the covering layer on the surface of the directional coupler structure (3) is composed of a directional coupler structure SiO2 lower cladding layer (13), a directional coupler structure SiO2 core layer (14), and a directional coupler structure SiO2 upper cladding layer (15); and the directional coupler structure amorphous silicon nitride is sequentially processed on the surface of the directional coupler structure SiO2 upper cladding layer (15) connected to the left interference arm by magnetron sputtering deposition. amorphous Sb2S3 phase change layer (16) of the directional coupler structure and an Al2O3 protective layer (18) of the directional coupler structure; amorphous Sb2S3 phase change layer (16) of the directional coupler structure and an Al2O3 protective layer (18) of the directional coupler structure are sequentially processed on the surface of the SiO2 upper cladding (15) of the directional coupler structure connected to the right interferometer arm by magnetron sputtering deposition, and the amorphous Sb2S3 phase change layer (16) of the directional coupler structure is processed by laser direct writing to obtain a laser-induced crystalline Sb2S3 phase change layer (17) of the directional coupler structure; The directional coupler structure amorphous Sb2S3 phase change layer (16) and the directional coupler structure laser-induced crystalline Sb2S3 phase change layer (17) are both modulation structures; Laser is used to modulate the refractive index of the Sb2S3 phase change layer in the directional coupler structure, and further to control the coupling coefficient of the output light of the left interference arm and the right interference arm in the Mach-Zehnder interferometer structure (2), thereby expanding the adjustment range of the splitting ratio.

5. A planar optical waveguide tunable optical splitter based on phase change material according to claim 3 or 4, characterized in that: The parameters of the laser are: wavelength 532 nm, power 5 mW, and scanning speed 10 μm / s.

6. A method for dynamically adjusting a planar optical waveguide tunable optical splitter based on phase change material according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: performing laser-induced directional crystallization on the Mach-Zehnder interferometer structure laser-induced crystalline Sb2S3 phase change layer (11) on the surface of the right interference arm of the Mach-Zehnder interferometer structure (2); Step 2: Control the splitting ratio of the output light of the Mach-Zehnder interferometer structure (2) after the laser-induced phase change; Step 3: Optimize the output light splitting ratio range of the directional coupler structure (3).

7. The method for dynamically adjusting a planar optical waveguide tunable optical splitter based on phase change material according to claim 6, characterized in that: The first step is specifically as follows: Step 1.1, use a 532nm continuous laser to scan the upper surface of the right interferometer arm in the Mach-Zehnder interferometer structure (2), set the laser power to 5mW, and the direct writing speed to 10μm / s, to form uniform and directional crystal stripes on the surface of the laser-induced crystalline Sb2S3 phase change layer (11) of the Mach-Zehnder interferometer structure of the right interferometer arm.

8. The method for dynamically adjusting a planar optical waveguide tunable optical splitter based on phase change material according to claim 7, characterized in that: The second step is specifically as follows: Step 2.1, constructing a loss measurement platform consisting of a 1550nm continuous laser light source (19) with a power of 3mW-10mW, a lens optical fiber (20), a planar optical waveguide tunable optical splitter (21), a collection objective lens (22), and an infrared camera (23); Step 2.2, turn on the switch of the 1550nm continuous laser light source (19), set the power to 5mW, adjust the position of the lens fiber (20), couple the input light into the planar optical waveguide tunable optical splitter (21), make the power meter read the maximum, and record the output optical power reading of the power meter; Step 2.3: Input 1550 nm laser light. After passing through the 1×2 Y-branch structure (1), the Mach-Zehnder interferometer structure without laser-induced phase change (2), and the directional coupler structure without laser-induced phase change (3), the measured output light has a splitting ratio of 50:50, which is set as the initial state. Step 2.4, on the surface of the left interferometer arm of the Mach-Zehnder interferometer structure (2), a laser with a power of 5 mW, a scanning speed of 10 μm / s, and a wavelength of 532 nm is used to induce uniform and directional crystal stripes on the surface, and the length of the crystallization region of the phase change material Sb2S3 is controlled by the laser scanning area; on the surface of the right interferometer arm of the Mach-Zehnder interferometer structure (2), the amorphous Sb2S3 phase change layer (10) of the Mach-Zehnder interferometer structure and the Al2O3 protective layer (12) covering it are selectively phase-changed; the laser action path is from the Al2O3 protective layer (12) of the Mach-Zehnder interferometer structure through the amorphous Sb2S3 phase change layer (10) of the Mach-Zehnder interferometer structure, and is focused on the interface of the laser-induced crystalline Sb2S3 phase change layer (11) of the Mach-Zehnder interferometer structure after laser induction; the direct writing area is controlled to scan along the axial direction of the right interferometer arm waveguide to form continuous crystal stripes; Step 2.5, inputting a 1550 nm laser, and recording in real time the splitting ratio of the output light when the laser-induced crystalline Sb2S3 phase change layer (11) of the Mach-Zehnder interferometer structure and the laser-induced crystalline Sb2S3 phase change layer (17) of the directional coupler structure undergo phase change when the 1×2 Y-branch structure (1) passes through the Mach-Zehnder interferometer structure (2) with laser-induced phase change in step 2.4, and the directional coupler structure (3) without laser-induced phase change; In step 2.6, it was recorded that when a 1550 nm laser was input, after passing through the 1×2 Y-branch structure (1), the Mach-Zehnder interferometer structure with laser-induced phase change (2), and the directional coupler structure without laser-induced phase change (3), the maximum controllable amplitude of the splitting ratio of the output light was 80:

20.

9. The method for dynamically adjusting a planar optical waveguide tunable optical splitter based on phase change material according to claim 8, characterized in that: The third step is specifically as follows: Step 3.1, on the surface of one arm of the directional coupler structure (3), a laser is used to induce a phase change in the phase change material Sb2S3 in its modulation structure, and the length of the crystallized region of the phase change material Sb2S3 is increased from 1 mm to 2 mm by controlling the laser scanning area; In step 3.2, a 1550nm laser is input. When it passes through the 1×2Y-branch structure (1), the Mach-Zehnder interferometer structure for laser-induced phase change (2), and the directional coupler structure for laser-induced phase change (3), the splitting ratio of the output light during the phase change of the laser-induced phase change material Sb2S3 is recorded in real time. The maximum control range of the splitting ratio is expanded from 80:20 to 99:1, realizing the dynamic adjustment of the planar optical waveguide tunable optical splitter.

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