Phase change photonic device and preparation method thereof

Abstract

The invention provides a phase change photonic device and a preparation method thereof, and relates to the technical field of semiconductors, and the preparation method of the phase change photonic device comprises the steps: preparing a ridge-type silicon waveguide; preparing a phase change material layer on the surface of the ridge-type silicon waveguide; then, according to the stage sequence, short pulses with different energy values are output through a laser in the pulse-by-pulse irradiation stage, the surface of the initial phase-change photonic device is irradiated in sequence, so that the phase-change material layer is cooled step by step according to the stage sequence, the microstructure of the phase-change material layer is adjusted in the step-by-step cooling process, and the phase-change photon synaptic weight is changed; and the final phase change photonic device is obtained. On the basis, the phase-change material layers on the ridge-type silicon waveguide are sequentially irradiated by utilizing multi-stage combined pulses in pulse-by-pulse irradiation stages, so that the phase-change material layers are gradually cooled according to the stage sequence, the microstructures of the phase-change material layers are adjusted in the step-by-step cooling process, and the phase-change photon synaptic weight is changed.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology. Specifically, it relates to a phase change photonic device and a method for preparing the same. Background Art

[0002] In recent years, phase change materials have made significant progress in frontier applications such as photonic neural networks, photonic weight banks, and convolutional accelerators, showing great application potential. The weight performance of a photonic synapse directly affects the accuracy of matrix multiplication, as well as the speed and energy consumption related to weight updates. Its performance is mainly restricted by two factors: one is the material characteristics of the device, and the other is the modulation method. Usually, the maximum theoretical optical contrast and phase change speed of the device are mainly improved by improving the modulation method.

[0003] Existing modulation methods are mainly divided into two categories: electrical modulation and optical modulation. Although optical modulation can reduce the thermal diffusion loss caused by the electrical modulation process, during the phase change corresponding to optical modulation, the change in the atomic arrangement will cause a change in the material bandgap, which will significantly affect the absorption efficiency of the pump light energy, posing a major obstacle to achieving precise optical modulation. At the same time, the crystallization rate of most phase change materials shows significant non-Arrhenius temperature dependence. For example, in a typical Ge2Sb2Te5 (GST) material, the crystallization rate can vary by up to 9 orders of magnitude in the range from the crystallization temperature to the melting temperature. Too low or too high a temperature will hinder effective crystal formation. The heating and cooling rates of phase change materials are also closely related to their final crystal structure and quality. After multiple phase change cycles, the material may experience elemental segregation, mainly due to stress effects and thermal gradients during the crystallization process, resulting in a gradual decline in device performance.

[0004] Based on this, there is an urgent need for a phase change photonic device solution that can overcome the deficiencies in the optoelectronic modulation method of phase change photonic devices in the prior art, adjust the weight performance of photonic synapses, and improve the accuracy of matrix multiplication. Summary of the Invention

[0005] The purpose of the embodiments of this application is to provide a phase change photonic device and a method for preparing the same, which can improve the weight performance of photonic synapses and increase the accuracy of matrix multiplication.

[0006] In a first aspect, this application provides a method for preparing a phase change photonic device. For any phase change photonic device, the preparation method includes the following steps: Prepare a ridge-shaped silicon waveguide; Prepare a phase change material layer on the surface of the ridge-shaped silicon waveguide to obtain an initial phase change photonic device; wherein, the phase change material layer covers the ridge-shaped silicon waveguide; Sequentially, a laser is used to irradiate short pulses with different energy values in each stage, and the surface of the initial phase-change photon device is irradiated in turn, so that the phase-change material layer cools down step by step according to the stage sequence, and the microstructure of the phase-change material layer is adjusted during the step-by-step cooling process to change the phase-change photon synaptic weight, obtaining the final phase-change photon device; Among them, the time lengths corresponding to each pulse irradiation stage are different. Optionally, sequentially, with the initial pulse irradiation stage as the first pulse irradiation stage, the steps of using a laser to irradiate short pulses with different energy values in each stage and irradiating the surface of the initial phase-change photon device in turn include: In the first pulse irradiation stage, the laser outputs a first pulse segment to heat the phase-change material layer to melt the phase-change material in the phase-change material layer; among them, the first pulse segment includes at least one short pulse with the same energy value; In the remaining pulse irradiation stages except the first pulse irradiation stage, the laser outputs the corresponding pulse segment to heat the phase-change material layer to adjust the temperature of the phase-change material to a preset temperature range, so that the phase-change material layer is in a microstructure switching state; Among them, the average value of the preset temperature range is less than the melting temperature of the phase-change material.

[0007] Optionally, the average value of the preset temperature range is equal to 350 °C.

[0008] Optionally, for any pulse irradiation stage, the steps of using a laser to irradiate short pulses with different energy values in each stage and irradiating the surface of the initial phase-change photon device in turn include: In the current pulse irradiation stage, the laser sequentially applies a plurality of short pulses with the same energy to the phase-change material layer from above the initial phase-change photon device at a first preset time interval; Among them, sequentially in each stage, the energy corresponding to each pulse irradiation stage gradually decreases.

[0009] Optionally, the first preset time interval is less than or equal to 30 ns.

[0010] Optionally, when sequentially including a first pulse irradiation stage, a second pulse irradiation stage, and a third pulse irradiation stage in chronological order, and the pulse energies corresponding to the first pulse irradiation stage, the second pulse irradiation stage, and the third pulse irradiation stage are the first pulse energy, the second pulse energy, and the third pulse energy respectively; and the time intervals corresponding to the first pulse irradiation stage, the second pulse irradiation stage, and the third pulse irradiation stage are the first time interval, the second time interval, and the third time interval respectively; the steps of using a laser to irradiate short pulses with different energy values in each stage and irradiating the surface of the initial phase-change photon device in turn include: In the first pulse irradiation stage, a laser is used to continuously output short pulses corresponding to a first pulse energy value in a first preset time interval to irradiate the phase change material layer; In the second pulse irradiation stage, a laser is used to sequentially output short pulses corresponding to a plurality of second pulse energy values in a second preset time interval to irradiate the phase change material layer; In the third pulse irradiation stage, a laser is used to sequentially output short pulses corresponding to a plurality of third pulse energies in a third preset time interval to irradiate the phase change material layer; Wherein, the second pulse energy value is less than the first pulse energy value and greater than the third pulse energy value.

[0011] Optionally, the end time of the first pulse irradiation stage is the same as the start time of the second pulse irradiation stage; there is a second preset time interval between the second pulse irradiation stage and the third pulse irradiation stage.

[0012] Optionally, the second time interval is 20 ns.

[0013] Optionally, along the direction of the ridge waveguide, the length of the phase change material layer is 4 μm and the thickness is 30 nm.

[0014] In a second aspect, the present application further provides a phase change photonic device, which is made by the manufacturing method described in any one of the first aspects above.

[0015] The phase change photonic device and its manufacturing method provided by the present application have the following beneficial effects: In the manufacturing method of the phase change photonic device in the present application, for any phase change photonic device, the manufacturing method includes the following steps: preparing a ridge silicon waveguide; and preparing a phase change material layer on the surface of the ridge silicon waveguide to obtain an initial phase change photonic device; wherein, the phase change material layer covers the optical waveguide layer; subsequently, in accordance with the stage sequence, a laser is used to irradiate the surface of the initial phase change photonic device with short pulses of different energy values in each pulse irradiation stage, so that the phase change material layer cools down step by step in accordance with the stage sequence, and during the step-by-step cooling process, the microstructure of the phase change material layer is adjusted to change the phase change photonic synaptic weight, thereby obtaining a final phase change photonic device; wherein, the time lengths corresponding to each pulse irradiation stage are different. Based on this, the present application uses multi-stage combined pulses to irradiate the phase change material layer on the ridge silicon waveguide in each pulse irradiation stage in sequence, so that the phase change material layer cools down step by step in accordance with the stage sequence, and during the step-by-step cooling process, the microstructure of the phase change material layer is adjusted to change the phase change photonic synaptic weight, thereby overcoming the deficiencies in the optoelectronic modulation method of phase change photonic devices in the prior art and improving the modulation depth, accuracy, speed and energy efficiency of photonic devices. Description of the Drawings

[0016] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a flowchart of the steps of the preparation method of the phase change photon device provided by the embodiment of the present application; Figure 2 It is a sub-step flowchart of step 200 in the embodiment of the present application; Figure 3 It is a schematic cross-sectional structure diagram corresponding to the fabricated ridge-shaped silicon waveguide in the embodiment of the present application; Figure 4 It is one of the schematic cross-sectional structure diagrams corresponding to the fabricated phase change material layer in the embodiment of the present application; Figure 5 It is another schematic cross-sectional structure diagram corresponding to the fabricated phase change material layer in the embodiment of the present application; Figure 6 It is the third schematic cross-sectional structure diagram corresponding to the fabricated phase change material layer in the embodiment of the present application; Figure 7 It is a sub-step flowchart of step 300 in the embodiment of the present application; Figure 8 ( a ) is one of the device test diagrams of the phase change photon device in the embodiment of the present application; Figure 8 ( b ) is another device test diagram of the phase change photon device in the embodiment of the present application; Figure 8 ( c ) is the third device test diagram of the phase change photon device in the embodiment of the present application.

[0018] Icon: 10 - Substrate; 11 - Ridge-shaped silicon waveguide; 12 - Phase change material layer; 13 - Protective layer; 14 - Thermal isolation layer. Detailed implementation manners

[0019] As described in the background art, the weight performance of the photonic synapse directly affects the accuracy of matrix multiplication, as well as the speed and energy consumption related to weight update. The prior art often uses electrical modulation method and optical modulation method to achieve the modulation of phase change materials, so as to improve the modulation contrast, accuracy, speed, linearity of the device, and at the same time reduce the modulation ability.

[0020] Compared with electrical modulation, optical modulation does not require an additional heating electrode structure and can directly heat the device using high-instantaneous-power laser pulses, further improving the modulation speed and significantly reducing the thermal diffusion loss during modulation. However, due to the stress effect and thermal gradient during the crystallization process, after multiple phase change cycles, the material may undergo elemental segregation, causing the device performance to gradually decline. Based on this, the present application provides a phase-change photonic device and a preparation method to overcome the above technical problems.

[0021] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0022] Please refer to Figure 1 , Figure 1 , which is a flowchart of the steps of the preparation method of the phase-change photonic device provided by the embodiment of the present application. For any phase-change photonic device, the preparation method includes step 100 and step 300.

[0023] Step 100: Prepare a ridge-type silicon waveguide.

[0024] Step 200: Prepare a phase-change material layer on the surface of the ridge-type silicon waveguide to obtain an initial phase-change photonic device.

[0025] Among them, the phase-change material layer covers the optical waveguide layer.

[0026] Step 300: According to the stage sequence, use a laser to irradiate the surface of the initial phase-change photonic device with short pulses of different energy values output by each pulse, so that the phase-change material layer cools down step by step according to the stage sequence, and adjust the microstructure of the phase-change material layer during the step-by-step cooling process to change the phase-change photonic synaptic weight, and obtain the final phase-change photonic device.

[0027] Among them, the time lengths corresponding to each pulse irradiation stage are different. In this embodiment, a phase-change material layer is prepared on the ridge-type silicon waveguide, and then the surface of the initial phase-change photonic device, especially the phase-change material layer, is irradiated step by step using a combined pulse output by a laser. That is, different energy pulses are combined to implement a combined pulse to replace the traditional two-step pulse modulation scheme, so that the phase-change material layer cools down step by step according to the stage sequence. By making full use of the non-Arrhenius crystallization characteristics of the phase-change material, the crystallization characteristics are improved, and too low or too high temperatures are avoided from hindering the formation of effective crystals; and the microstructure of the phase-change material layer is adjusted during the step-by-step cooling process, that is, the state is switched between the two microstructures of amorphous and crystalline. For example, during the step-by-step cooling process, the phase-change material is in a coexistence stage of amorphous state and crystalline state, so that the transmittance of the current phase-change photonic device is converted between the maximum transmittance Tmax and the minimum transmittance Tmin, and then the adjustment of the phase-change photonic synaptic weight is realized, and the final phase-change photonic device is obtained.

[0028] Based on this, the present application sets a combined pulse modulation method based on the multi-stage slow cooling characteristics of the crystallization process of the phase change material, which can erase the amorphous state more energy-efficiently and stably, while suppressing the switching between multiple crystal structures, improving the precision and linearity of the synaptic programmable state number of the phase change photonic device, and optimizing the weight configuration in the neural network.

[0029] Please, on the basis of Figure 1 , refer to Figure 2 , Figure 2 which shows the step flow chart of step 100 in this embodiment. The step 100 of fabricating a ridge-shaped silicon waveguide in this embodiment includes the following steps: Step 101: Provide a substrate.

[0030] Step 102: Set a ridge-shaped silicon waveguide on the substrate.

[0031] Please, on the basis of Figure 2 , refer to Figure 3 , Figure 3 which shows the corresponding cross-sectional structure schematic diagram after fabricating the ridge-shaped silicon waveguide in step 100. In this embodiment, an optical waveguide can be fabricated on a SOI substrate 10 (Silicon-On-Insulator), for example, by lithography and etching with an electron beam on the SOI substrate to obtain a ridge-shaped silicon waveguide 11.

[0032] Please, on the basis of Figure 3 , refer to Figure 4 , Figure 4 which shows the corresponding cross-sectional structure schematic diagram after fabricating the phase change material layer in step 200. After obtaining the ridge-shaped silicon waveguide 11, in this embodiment, a phase change material layer 12 can be continuously fabricated on the surface of the ridge-shaped silicon waveguide 11. The material for fabricating the phase change material layer 12 in this embodiment can be Ge2Sb2Te5.

[0033] In a possible implementation manner, the Ge2Sb2Te5 material can be directly deposited onto the optical waveguide by using a magnetron sputtering system on the surface of the ridge-shaped silicon waveguide 11, and then ultraviolet lithography patterning is performed to obtain the phase change material layer 12. In another possible implementation manner, please, on the basis of Figure 4 , refer to Figure 5 , Figure 5 which shows another corresponding cross-sectional structure schematic diagram after fabricating the phase change material layer 12 in step 200. After fabricating the phase change material layer 12, to avoid oxidation during modulation, a protective layer 13 can be fabricated on the surface of the above-mentioned phase change material layer 12. The fabrication method of the protective layer 13 can also be formed by ultraviolet lithography patterning and magnetron sputtering deposition.

[0034] Among them, along the direction of the ridge waveguide, the length of the phase change material layer 12 is 4 μm and the thickness is 30 nm. Further, the width of the phase change material layer 12 is slightly wider than the width of the ridge waveguide.

[0035] In another possible implementation, in order to avoid heat leakage in this embodiment and at the same time avoid large losses in the transmission of optical signals, which may affect the device efficiency, a thermal isolation layer 14 may also be provided on the phase change material layer in this embodiment. The thermal isolation layer 14 covers the optical waveguide layer, that is, the surface of the ridge silicon waveguide 11, and its width is greater than or equal to the width of the optical waveguide layer. Please refer to Figure 6 , Figure 6 FIG. shows another cross-sectional structure diagram corresponding to the production of the phase change material layer 11 in step 200. Among them, the phase change material layer 12 is provided on the surface of the thermal isolation layer 14; the protective layer 13 is provided on the surface of the phase change material layer 12.

[0036] In this embodiment, the material for preparing the thermal isolation layer is a material containing low thermal conductivity at the nanoscale. For example, silicon dioxide (SiO2), stainless steel, titanium alloy, silicon nitride (Si3N 4） , aluminum oxide (Al2O3), boron nitride (BN), microporous nano partition (Cr), graphene (C), and Al-B-O system compounds, etc., any one of the materials with low thermal conductivity and thermal stability.

[0037] Please, on the basis of Figure 1 , refer to Figure 7 , Figure 7 FIG. shows the sub-step flow chart of step 300 in this embodiment. Step 300 of the final phase change photon device in this embodiment includes step 301 and step 302.

[0038] Step 301: In the first pulse irradiation stage, use a laser to output a first pulse segment to heat the phase change material layer to melt the phase change material in the phase change material layer.

[0039] Among them, the first pulse segment includes at least one short pulse with the same energy value.

[0040] Step 302: In the remaining pulse irradiation stages except the first pulse irradiation stage, use a laser to output the corresponding pulse segment to heat the phase change material layer to adjust the temperature of the phase change material to a preset temperature range, so that the phase change material layer is in a microstructural switching state.

[0041] Among them, the average value of the preset temperature range is less than the melting temperature of the phase change material.

[0042] In this embodiment, a spatial pump light can be used to construct a combined pulse, and then the phase change material layer is irradiated stage by stage. In the first pulse irradiation stage, high pulse energy can be preferentially output to heat the device temperature above the material melting temperature, such as above 600 degrees Celsius, so as to facilitate the crystallization of the phase change material. In other irradiation stages except the first pulse irradiation stage, during the process of gradually decreasing the temperature, the phase change material is switched between two microstructures of amorphous and crystalline.

[0043] In this embodiment, in other irradiation stages except the first pulse irradiation stage, the device temperature can be maintained within the optimal crystallization range, for example, 350 °C, which is the mean value of the above preset temperature range, so as to adjust the phase change photon synaptic weight.

[0044] In this embodiment, for any pulse irradiation stage, the steps of using a laser to sequentially irradiate the surface of the initial phase change photon device with short pulses of different energy values in each pulse irradiation stage are as follows: In the current pulse irradiation stage, a laser is used to sequentially apply a plurality of short pulses with the same energy to the phase change material layer from above the initial phase change photon device at a first preset time interval.

[0045] Among them, in the sequential stages, the energy corresponding to each pulse irradiation stage gradually decreases.

[0046] In a possible implementation manner, in any pulse irradiation stage, a spatial pump light can be used to use a 1550 nm laser as a pump light source, and short pulses with the same energy are sequentially output at a first time interval, and are vertically irradiated on the surface of the phase change photon device from above the device for modulation. In this embodiment, the first preset time interval can be less than or equal to 30 ns.

[0047] Taking the first pulse irradiation stage as an example, a laser can be used to output a first pulse segment with a pulse energy of 84 pJ (i.e., the following first pulse energy) to heat the phase change material layer to melt the phase change material in the phase change material layer.

[0048] Among them, the first pulse segment can include one short pulse. If the first pulse segment includes multiple short pulses, there is a certain time interval between the output times of each short pulse, that is, the first time interval, and the first time interval can be 20 ns.

[0049] Based on this, this application uses a pump light pulse with high energy in the first pulse irradiation stage to heat the phase change material to the melting temperature, and due to the rapid annealing process, it will remain in the disordered amorphous state. Subsequently, the phase change material is heated above the crystallization temperature for a period of time based on the pump light with low energy, so as to reorder the atoms into the crystalline state.

[0050] Based on the above steps, this embodiment provides an example to fully demonstrate the preparation method provided by this application.

[0051] After the initial phase-change photon device is prepared according to steps 100 to 200, in chronological order, it successively includes a first pulse irradiation stage, a second pulse irradiation stage, and a third pulse irradiation stage. The pulse energies corresponding to the first pulse irradiation stage, the second pulse irradiation stage, and the third pulse irradiation stage are the first pulse energy, the second pulse energy, and the third pulse energy respectively; when the time intervals corresponding to the first pulse irradiation stage, the second pulse irradiation stage, and the third pulse irradiation stage are the first time interval, the second time interval, and the third time interval respectively; in this embodiment, the specific step 300 of using a laser to irradiate the surface of the initial phase-change photon device with short pulses of different energy values in each pulse irradiation stage is as follows: In the first pulse irradiation stage, use a laser to continuously output a short pulse corresponding to a first pulse energy value in the first preset time interval to irradiate the phase-change material layer.

[0052] In the second pulse irradiation stage, use a laser to successively output multiple short pulses corresponding to second pulse energy values in the second preset time interval to irradiate the phase-change material layer.

[0053] In the third pulse irradiation stage, use a laser to successively output multiple short pulses corresponding to the third pulse energy in the third preset time interval to irradiate the phase-change material layer.

[0054] Among them, the second pulse energy value is less than the first pulse energy value and greater than the third pulse energy value.

[0055] Taking the start time when the pulse is applied in the first pulse irradiation stage as the starting time in this embodiment, to ensure that the phase-change material is fully melted, the time length of the first pulse irradiation stage in this embodiment can be 20 ns. Based on this, in this embodiment, a light pulse with a pulse energy of 84 pJ can be output in the 0 - 20 ns stage and act on the surface of the phase-change photon device.

[0056] Subsequently, it can directly enter the second pulse irradiation stage at the end time of the first pulse irradiation stage, that is, the end time of the first pulse irradiation stage is the same as the start time of the second pulse irradiation stage. The pulse energy corresponding to the second pulse irradiation stage in this embodiment can be 67 pJ. To ensure the temperature stability during the step-by-step cooling process, multiple light pulses with the same pulse energy and a certain time interval can be output. In addition, the time length corresponding to the second pulse irradiation stage in this embodiment can be 60 ns, that is, in this embodiment, multiple light pulses with a pulse energy of 67 pJ can be output in the 20 - 80 ns stage and act on the surface of the phase-change photon device, where the interval time between each light pulse is 20 ns.

[0057] Similarly to the above steps, the time length corresponding to the third pulse irradiation stage can be 120 ns, and the pulse energy corresponding to the third pulse irradiation stage can be 56 pJ. That is, in this embodiment, within the 80 - 200 ns stage, multiple optical pulses with a pulse energy of 56 pJ can be output and act on the surface of the phase change photon device, where the interval time between each optical pulse is 20 ns.

[0058] In another possible implementation manner, to combine the multi - stage slow cooling characteristic of the phase change material crystallization process to ensure the temperature stability of the phase change material crystallization process, there may be a certain time interval, such as 20 ns, between the third pulse irradiation stage and the third pulse irradiation stage in this embodiment.

[0059] Based on this, the present application can suppress the element segregation caused by temperature gradient and non - uniform stress during the crystallization process with optical pulses having a short time interval and high energy, as well as a modulation scheme with gradually decreasing energy in sequence, greatly improving the durability of the device.

[0060] Based on the same inventive concept, an embodiment of the present application also provides a phase change photon device, which is made by the preparation method described in any one of the above first aspects.

[0061] In addition, please refer to Fig. 8( a ), Fig. 8( b ), Fig. 8( c ), where Fig. 8( a ) is the state diagram of the photon device with different - thickness phase change materials under combined - pulse modulation; Fig. 8( b ) is the durability and stability test diagram of the phase change photon device under combined - pulse modulation; Fig. 8( c ) is the programming state number accuracy and linearity test diagram of the phase change photon device under combined - pulse modulation. It can be seen from Fig. 8( a ), Fig. 8( b ), Fig. 8( c ) that the phase change photon device prepared in the present application has the following beneficial effects: 1. High optical absorption contrast. Based on the 4 - μm - long and 30 - nm - thick phase change material unit covered on the straight waveguide, the device transmission contrast can reach 31.2 dB.

[0062] 2. High time and energy efficiency for the crystallization operation of the device. The total time required for the device to be completely crystallized is 200 ns, and the energy is 107 pJ.

[0063] 3. High durability of the device. After 108 cycles of crystallization and amorphous state writing and erasing, the device can still work normally.

[0064] 4. The device programming has high linearity, and the weight states of the device in multiple programming processes have good linearity.

[0065] Based on the same inventive concept, an embodiment of the present application also provides a phase change photonic device, which is made by the preparation method described in any one of the above first aspects.

[0066] In summary, for the phase change photonic device and its preparation method in the present application, for any phase change photonic device, the preparation method includes the following steps: preparing a ridge-shaped silicon waveguide; and preparing a phase change material layer on the surface of the ridge-shaped silicon waveguide to obtain an initial phase change photonic device; wherein the phase change material layer covers the optical waveguide layer; subsequently, in accordance with the stage sequence, using a laser to irradiate the surface of the initial phase change photonic device with short pulses of different energy values in each pulse, so that the phase change material layer cools down step by step in accordance with the stage sequence, and adjusting the microstructure of the phase change material layer during the step-by-step cooling process to change the phase change photonic synaptic weight, thereby obtaining a final phase change photonic device; wherein the time lengths corresponding to each pulse irradiation stage are different.

[0067] Based on this, the present application uses multi-stage combined pulses to irradiate the phase change material layer on the ridge-shaped silicon waveguide pulse by pulse, so that the phase change material layer cools down step by step in accordance with the stage sequence, and adjusts the microstructure of the phase change material layer during the step-by-step cooling process to change the phase change photonic synaptic weight, thereby overcoming the deficiencies in the photoelectric modulation method of phase change photonic devices in the prior art and improving the modulation depth, precision, speed, and energy efficiency of photonic devices.

[0068] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. Also, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point, the displayed or discussed couplings or direct couplings or communication connections to each other can be through some communication interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0069] In addition, the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0070] Furthermore, in each embodiment of the present application, each functional module may be integrated together to form an independent part, or each module may exist alone, or two or more modules may be integrated to form an independent part.

[0071] It should be noted that if a function is implemented in the form of a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs.

[0072] In this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0073] The above are only the embodiments of the present application and are not used to limit the protection scope of the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for preparing a phase change photonic device, characterized in that, For any phase-change photonic device, the preparation method includes the following steps: Prepare a ridge-type silicon waveguide; Prepare a phase-change material layer on the surface of the ridge-type silicon waveguide to obtain an initial phase-change photonic device; wherein, the phase-change material layer covers the ridge-type silicon waveguide; In accordance with the stage sequence, use a laser to irradiate short pulses with different energy values in each pulse irradiation stage, and sequentially irradiate the surface of the initial phase-change photonic device, so that the phase-change material layer cools down stage by stage in accordance with the stage sequence, and adjust the microstructure of the phase-change material layer during the gradual cooling process to change the phase-change photonic synaptic weight, obtaining a final phase-change photonic device; Among them, the time lengths corresponding to each of the pulse irradiation stages are different.

2. The preparation method according to claim 1, characterized in that, In accordance with the stage sequence, with the initial pulse irradiation stage as the first pulse irradiation stage, the step of using a laser to irradiate short pulses with different energy values in each pulse irradiation stage and sequentially irradiating the surface of the initial phase-change photonic device includes: In the first pulse irradiation stage, use the laser to output a first pulse segment to heat the phase-change material layer to melt the phase-change material in the phase-change material layer; wherein, the first pulse segment includes at least one short pulse with the same energy value; In the remaining pulse irradiation stages except the first pulse irradiation stage, use the laser to output the corresponding pulse segment to heat the phase-change material layer to adjust the temperature of the phase-change material to a preset temperature range, so that the phase-change material layer is in a microstructure switching state; Among them, the average value of the preset temperature range is less than the melting temperature of the phase-change material.

3. The preparation method according to claim 2, wherein, The average value of the preset temperature range is equal to 350 °C.

4. The preparation method according to claim 1, characterized in that, For any of the pulse irradiation stages, the step of using a laser to irradiate short pulses with different energy values in each pulse irradiation stage and sequentially irradiating the surface of the initial phase-change photonic device includes: In the current pulse irradiation stage, use the laser to sequentially apply a plurality of short pulses with the same energy to the phase-change material layer from above the initial phase-change photonic device at a first preset time interval; Among them, in accordance with the stage sequence, the energy corresponding to each of the pulse irradiation stages gradually decreases.

5. The preparation method according to claim 4, characterized in that, The first preset time interval is less than or equal to 30 ns.

6. The preparation method according to any one of claims 1 to 5, characterized in that When, in accordance with the time sequence, it sequentially includes a first pulse irradiation stage, a second pulse irradiation stage, and a third pulse irradiation stage, and the pulse energies corresponding to the first pulse irradiation stage, the second pulse irradiation stage, and the third pulse irradiation stage are the first pulse energy, the second pulse energy, and the third pulse energy respectively; and the time intervals corresponding to the first pulse irradiation stage, the second pulse irradiation stage, and the third pulse irradiation stage are the first time interval, the second time interval, and the third time interval respectively; the step of using a laser to irradiate short pulses with different energy values in each pulse irradiation stage and sequentially irradiating the surface of the initial phase-change photonic device includes: In the first pulse irradiation stage, use the laser to continuously output a short pulse corresponding to a first pulse energy value in the first preset time interval to irradiate the phase-change material layer; In the second pulse irradiation stage, the laser is used to sequentially output short pulses corresponding to a plurality of second pulse energy values in a second preset time interval to irradiate the phase change material layer; In the third pulse irradiation stage, the laser is used to sequentially output short pulses corresponding to a plurality of third pulse energies in a third preset time interval to irradiate the phase change material layer; wherein the second pulse energy value is less than the first pulse energy value and greater than the third pulse energy value.

7. The preparation method according to claim 6, characterized in that, The end time of the first pulse irradiation stage is the same as the start time of the second pulse irradiation stage; there is a second preset time interval between the second pulse irradiation stage and the third pulse irradiation stage.

8. The preparation method according to claim 6, characterized in that, The second time interval is 20 ns.

9. The preparation method according to claim 1, wherein Along the ridge waveguide direction, the length of the phase change material layer is 4 μm and the thickness is 30 nm.

10. A phase change photon device, characterized in that, The phase change photonic device is made by the preparation method according to any one of claims 1 to 9.

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