Beam splitter and method for dynamically regulating and controlling light splitting

Abstract

The invention relates to the technical field of silicon-based photonic integrated chips, and discloses a beam splitter, which comprises a directional coupler and regulation and control equipment, an optical waveguide of the directional coupler is covered with a phase change material, the regulation and control equipment is used for switching phase change states of the phase change material, the phase change states of the phase change material comprise a crystalline state, an amorphous state and a plurality of intermediate states, and the phase change states of the phase change material are different. The intermediate state is a state between an amorphous state and a crystalline state. The phase change state of the phase change material on the optical waveguide of the directional coupler is changed, so that the splitting ratio is dynamically regulated and controlled. The invention also provides a method for dynamically regulating and controlling the splitting ratio by the beam splitter, the phase change state of the phase change material on the optical waveguide is changed, three or more splitting ratios can be obtained by utilizing a crystalline state, an amorphous state and a plurality of intermediate states, and in the regulation and control process, the degree of applied external stimulation is gradually increased, so that the splitting ratio is gradually increased, and the splitting ratio can be regulated and controlled. And the splitting ratio is dynamically and continuously regulated and controlled. The method has higher flexibility, adaptability and stability.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon-based photonic integrated chips, and particularly to a beam splitter and a method for dynamically regulating the splitting ratio. Background Art

[0002] With the development of communication technologies, the demands for optical fiber communication and optical computing are continuously increasing. However, traditional optical components are difficult to achieve high integration due to problems such as large volume and high cost, and cannot meet the requirements of modern communication. To improve the overall integration of communication systems, photonic integrated circuits have received extensive attention. With the continuous expansion of the on-chip data processing scale, they are currently developing towards large scale, low cost, and high performance.

[0003] Traditional beam splitters mainly include flat beam splitters and cubic beam splitters, which achieve the beam splitting effect by two beam splitting principles. One is to design and implement specific film reflectivity and transmittance based on Fresnel's law, so that a certain proportion of the incident light is reflected, while the other part of the incident light is transmitted; the other solution is to use the thin-film interference principle to design the thickness and refractive index of multilayer films, so as to realize the interference of reflected light at different interfaces and optimize the beam splitting performance. However, this type of beam splitter has a large volume, and the installation and alignment are relatively complex, making it difficult to achieve high-density photonic integration.

[0004] To improve the integration and construct a multifunctional and high-density photonic system, various design schemes of on-chip beam splitters have been proposed. The on-chip beam splitter is mainly a core component used to realize the distribution and combination of optical signals in a photonic integrated circuit, including three common beam splitting schemes: Y-type beam splitter, multimode interference beam splitter, and directional coupler. Among them, the Y-type beam splitter mainly uses the forked structure of the waveguide itself to achieve the equal division of light. The design structure is simple, but it has high requirements for the bending control of the waveguide; the multimode interference beam splitter is mainly based on the self-imaging principle in a multimode waveguide, which can evenly distribute the input light to multiple output ports, and has the advantages of broadband and high tolerance. Combined with liquid crystal materials, it can be electro-optically regulated to adjust its splitting ratio, but it has disadvantages such as slow response speed and sensitivity to environmental temperature; the directional coupler mainly uses the evanescent field coupling between adjacent waveguides to achieve energy exchange. Compared with the previous two schemes, this scheme is more flexible and controllable, and can be designed to achieve any splitting ratio, but it has high requirements for the process.

[0005] Although traditional parallel two-waveguide directional couplers, photonic crystal directional couplers designed based on defect lattices, and directional coupler schemes for regulating the splitting ratio by adjusting the waveguide length and position can all achieve the regulation of different splitting ratios, these schemes all achieve the regulation of the splitting ratio by adjusting the device design scheme. It is necessary to perform design adjustments before device fabrication to achieve the expected splitting ratio, and cannot achieve the true dynamic regulation function of the splitting ratio. Summary of the Invention

[0006] The object of the present invention is to provide a beam splitter capable of achieving multiple splitting ratios during use and a method for dynamically regulating the splitting ratio.

[0007] To achieve the above object, the present invention provides a beam splitter, comprising a directional coupler and a regulation device. The directional coupler includes an optical waveguide, and a phase change material is covered on the optical waveguide. The regulation device is used to switch the phase change state of the phase change material. Wherein, the phase change state of the phase change material includes a crystalline state, an amorphous state, and several intermediate states, and the intermediate state is a state between the amorphous state and the crystalline state.

[0008] As a preferred solution, the regulation device is a thermal control device, an optical control device, or an electric control device.

[0009] As a preferred solution, the optical waveguide includes two side waveguides and an intermediate waveguide. The intermediate waveguide is arranged between the two side waveguides, so that the directional coupler is a three-waveguide directional coupler, and the phase change material is arranged on the intermediate waveguide.

[0010] As a preferred solution, the coupling region length of the directional coupler is the coupling length required when the phase change material is in the crystalline state, and the coupling length of the phase change material in the crystalline state is twice that in the amorphous state.

[0011] As a preferred solution, the two side waveguides are parallel, so that the directional coupler supports two symmetric modes and one anti-symmetric mode. The effective refractive indices of the two symmetric modes are respectively and , the effective refractive index of the anti-symmetric mode is , and the values of the effective refractive indices of the three supermodes satisfy: .

[0012] The present invention also provides a method for dynamically regulating the splitting ratio of a beam splitter, comprising: Covering a phase change material on the optical waveguide of the directional coupler of the beam splitter; By controlling the phase change degree of the phase change material, making the phase change material in different phase change states, and performing dynamic regulation of the splitting ratio. Wherein, the phase change state includes a crystalline state, an amorphous state, and several intermediate states, and the intermediate state is a state between the amorphous state and the crystalline state.

[0013] As a preferred solution, the step of making the phase change material in different phase change states by controlling the phase change degree of the phase change material includes: Changing the phase change state of the phase change material by thermal control, optical control, or electric control.

[0014] As a preferred embodiment, by controlling the phase change degree of the phase change material to make the phase change material in different phase change states, the dynamic regulation of the splitting ratio is performed, including: Determine the required splitting ratio; Obtain the coupling power ratio diagram of the output ports of the beam splitter with different phase change degrees; According to the required splitting ratio and the coupling power ratio diagram, obtain the phase change degree required by the phase change material; Determine the regulation parameters according to the phase change degree required by the phase change material; Apply an external stimulus to the phase change material according to the regulation parameters.

[0015] As a preferred embodiment, obtaining the coupling power ratio diagram of the output ports of the beam splitter with different phase change degrees includes: Obtain the geometric parameters and material parameters of the directional coupler; According to the geometric parameters and material parameters of the directional coupler, obtain the coupling power ratio diagram of the output ports of the beam splitter with different phase change degrees.

[0016] As a preferred embodiment, in applying an external stimulus to the phase change material according to the regulation parameters, the phase change degree of the phase change material is obtained by measuring the dielectric constant of the phase change material.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: In the present invention, by arranging a phase change material on the optical waveguide of the directional coupler and changing the phase change state of the phase change material, the effective refractive index is changed, and then the splitting ratio is changed. The phase change state of the phase change material in the present invention is not only the crystalline state and the amorphous state, but also the intermediate state between the crystalline state and the amorphous state, so that the beam splitter has three or more splitting ratios. When in use, by changing the phase change state of the phase change material, the splitting ratio of the beam splitter can be dynamically regulated. Description of the Drawings

[0018] Figure 1 is the top view of the beam splitter according to the embodiment of the present invention.

[0019] Figure 2 is the side view of the beam splitter according to the embodiment of the present invention.

[0020] Figure 3 is the electric field distribution diagram of the symmetric mode of the 1550nm non-crystalline three-waveguide directional coupler of the silicon-based chalcogenide phase change material according to the embodiment of the present invention.

[0021] Figure 4 is the electric field distribution diagram of the anti-symmetric mode of the 1550nm non-crystalline three-waveguide directional coupler of the silicon-based chalcogenide phase change material according to the embodiment of the present invention.

[0022] Figure 5It is the distribution diagram of the symmetric mode two electric fields of the 1550nm amorphous three-waveguide directional coupler of the silicon-based chalcogenide phase change material according to the embodiment of the present invention.

[0023] Figure 6 It is the flowchart of the method for dynamically regulating the splitting ratio of the beam splitter according to the embodiment of the present invention.

[0024] Figure 7 It is the schematic diagram of the coupling power ratio of the output ports of the beam splitter when the silicon-based chalcogenide phase change material is in the fully crystalline state and m = 1 according to the embodiment of the present invention.

[0025] Figure 8 It is the schematic diagram of the coupling power ratio of the output ports of the beam splitter when the silicon-based chalcogenide phase change material is in the amorphous state and m = 0 according to the embodiment of the present invention.

[0026] Figure 9 It is the schematic diagram of the coupling power ratio of the output ports of the beam splitter when the crystallization degree of the chalcogenide phase change material is m = 0.2 according to the embodiment of the present invention.

[0027] Figure 10 It is the schematic diagram of the coupling power ratio of the output ports of the beam splitter when the crystallization degree of the chalcogenide phase change material is m = 0.3 according to the embodiment of the present invention.

[0028] Figure 11 It is the schematic diagram of the coupling power ratio of the output ports of the beam splitter when the crystallization degree of the chalcogenide phase change material is m = 0.5 according to the embodiment of the present invention.

[0029] Figure 12 It is the schematic diagram of the coupling power ratio of the output ports of the beam splitter when the crystallization degree of the chalcogenide phase change material is m = 0.7 according to the embodiment of the present invention.

[0030] Figure 13 It is the schematic diagram of the coupling power ratio of the output ports of the beam splitter when the crystallization degree of the chalcogenide phase change material is m = 0.8 according to the embodiment of the present invention.

[0031] Figure 14 It is the schematic diagram of the coupling power ratio of the output ports of the beam splitter when the phase change material Sb2Se3 has different crystallization degrees according to the embodiment of the present invention.

[0032] In the figure, 100 - side waveguide; 200 - middle waveguide; 300 - phase change material; 400 - silicon substrate; 500 - buried oxide layer; 600 - protective layer; 700 - input waveguide; 800 - output waveguide. Specific Embodiments

[0033] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0034] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0035] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In addition, in the description of the present invention, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0037] Embodiment 1 As Figures 1 to 13 shown, a beam splitter according to a preferred embodiment of an embodiment of the present invention includes a directional coupler and a regulation device. The directional coupler includes an optical waveguide, and a phase change material is covered on the optical waveguide. The regulation device is used to switch the phase change state of the phase change material. Among them, the phase change state of the phase change material includes a crystalline state, an amorphous state, and several intermediate states, and the intermediate state is a state between the amorphous state and the crystalline state. In this embodiment, by providing a phase change material on the optical waveguide of the directional coupler and changing the phase change state of the phase change material, the effective refractive index is changed, and further the splitting ratio is changed. The phase change state of the phase change material in this embodiment is not only the crystalline state and the amorphous state, but also uses the intermediate state between the crystalline state and the amorphous state, so that the beam splitter has three or more splitting ratios. When in use, by changing the phase change state of the phase change material, the splitting ratio of the beam splitter can be dynamically regulated.

[0038] Optionally, the regulation device is a thermal control device, an optical control device or an electrical control device. That is, when in use, the phase change state of the phase change material can be changed by temperature control, optical control or electrical control, etc.

[0039] In this embodiment, the phase change material is a chalcogenide phase change material, which has the characteristic of non-volatility, further optimizing the stability of the splitting ratio of the dynamically tunable beam splitter, enabling the device to have a certain anti-interference ability, and not requiring continuous energy input to maintain the splitting ratio. Optionally, the phase change material is Sb2Se3.

[0040] The crystallization of the phase change material Sb2Se3 proceeds step by step. Before complete crystallization, there are intermediate states between the amorphous state and the crystalline state, and due to its non-volatile characteristics, these intermediate states can also exist stably. Therefore, during the crystallization process, various intermediate states can be obtained through external stimuli such as temperature control, light control, or electrical control, which is beneficial to achieving continuous control in dynamic regulation, that is, quasi-continuous regulation. By adjusting the phase change state of Sb2Se3, the effective refractive index of the intermediate waveguide is changed, thereby achieving the splitting requirement of any ratio.

[0041] The crystallization process of Sb2Se3 is accompanied by the growth of crystal nuclei, and continuous heating is required to be more conducive to crystallization. And the transformation from the crystalline state to the amorphous state needs to experience a temperature higher than the melting temperature of the material and then a rapid cooling process. The temperature change can be controlled by external stimuli to regulate the transformation between the crystalline state and the amorphous state, thereby achieving the regulation of the splitting ratio.

[0042] Embodiment 2 The difference between this embodiment and Embodiment 1 is that on the basis of Embodiment 1, this embodiment further describes the directional coupler.

[0043] The directional coupler in this embodiment adopts a three-waveguide directional coupler. Compared with the traditional two-waveguide coupler, the three-waveguide directional coupler has more degrees of freedom and can adjust the waveguide distance and coupling length to regulate the supermode phase difference.

[0044] In this embodiment, the optical waveguide includes two side waveguides 100 and an intermediate waveguide 200. The intermediate waveguide 200 is arranged between the two side waveguides 100, making the directional coupler a three-waveguide directional coupler, and the phase change material 300 is arranged on the intermediate waveguide 200.

[0045] In addition, the directional coupler in this embodiment further includes a silicon substrate 400, a buried oxide layer 500, and a protective layer 600. The buried oxide layer 500 is arranged on the silicon substrate 400. The intermediate waveguide 200 and the two side waveguides 100 are arranged on the buried oxide layer 500. The phase change material 300 covers the intermediate waveguide 200. The protective layer 600 is arranged on the surfaces of the side waveguide 100, the intermediate waveguide 200, the phase change material 300, the silicon substrate 400, and the buried oxide layer 500, and the protective layer 600 wraps the entire device surface. The material of the buried oxide layer 500 is silicon dioxide. The side waveguide 100 and the intermediate waveguide 200 are both ridge-type silicon waveguides, and a hybrid waveguide is formed by covering the phase change material 300 on the intermediate waveguide 200. The protective layer 600 uses alumina material.

[0046] The three-waveguide directional coupler realizes energy distribution by using the interaction of evanescent fields among three closely arranged waveguides. By designing appropriate waveguide spacing and coupling length, its coupling can occur in the crystalline state. Assume that the coupling length in the amorphous state is LC1 and the coupling length in the crystalline state is LC2. When Sb2Se3 is in the crystalline state and the coupling length is LC2, the optical signal is output from the Cross port; by adjusting the coupling region length of the device to LC1, its coupling can also occur in the amorphous state, that is, when Sb2Se3 is in the amorphous state, the optical signal is output from the Cross port.

[0047] In this embodiment, the coupling region length of the directional coupler is the coupling length required when the phase change material is in the crystalline state, and the coupling length of the phase change material in the crystalline state is twice that in the amorphous state. This design enables the beam splitter to satisfy the quasi-continuous regulation of the coupling power ratio between the output ports Cross and Bar between 1:0 and 0:1. The degree of crystallization of the material can be adjusted by external stimulation, thereby changing the effective refractive index and realizing the dynamic regulation function of the splitting ratio.

[0048] A three-waveguide directional coupler with the coupling length in the crystalline state being twice that in the amorphous state is designed, and LC2 is selected as the final coupling length of the device. In the amorphous state, the effective refractive indices among the three waveguides form an arithmetic progression, and the device satisfies the phase matching of three supermodes, and coupling occurs between the waveguides. Since LC2 is twice LC1, there is a phase difference between the two modes , and the light is output from the Bar port. In the crystalline state, the effective refractive index of the middle waveguide becomes larger, greater than the effective refractive indices of the two side waveguides. At this time, the phase matching of the three supermodes is not satisfied. Since the coupling length is LC2, there is a phase difference between the two modes , and the optical signal is coupled to the Cross port for output.

[0049] The two side waveguides of the three-waveguide directional coupler in this embodiment are parallel, enabling the directional coupler to support two symmetric modes and one antisymmetric mode. The effective refractive indices of the two symmetric modes are respectively and , and the effective refractive index of the antisymmetric mode is . The values of the effective refractive indices of the three supermodes satisfy: .

[0050] The three-waveguide directional coupler structure has two symmetric modes and one antisymmetric mode. Using the commercial software Ansys Lumerical Mode for simulation, these three modes can be obtained. When the phase change material is in the amorphous state, the simulation of the electric field distribution of the three supermodes of the three-waveguide directional coupler at 1550 nm is as shown in Figure 3 、 Figure 4 、 Figure 5 .

[0051] Figure 3 and Figure 5 are two symmetric modes of a three - waveguide directional coupler, Figure 4 is an antisymmetric mode of a three - waveguide directional coupler. Using the software Ansys Lumerical Mode to simulate and design the model, the effective refractive indices of the three supermodes can be obtained. Let the effective refractive indices of the two symmetric modes be and respectively, and the effective refractive index of the antisymmetric mode is . When the values of the effective refractive indices of the three supermodes satisfy the following formula: the coupling efficiency of the three - waveguide directional coupler can reach the maximum value.

[0052] Among them, the coupling length L that the device needs to satisfy can be calculated by the following formula:

[0053] where is the optical wavelength, is the effective refractive index of the first symmetric mode, is the effective refractive index of the antisymmetric mode.

[0054] Through simulation optimization and calculation using the commercial software Ansys Lumerical Mode, adjust the interval width value between the waveguides of the three - waveguide directional coupler and the width value of the silicon waveguide for growing phase - change material, so as to achieve the relationship that the coupling length in the crystalline state is twice that in the amorphous state, and achieve the effect that the ratio of Bar to Cross is 0:1 in the crystalline state and 1:0 in the amorphous state; and try to satisfy the arithmetic - progression relationship between the effective refractive indices of the three supermodes to make the coupling efficiency of the three - waveguide directional coupler reach the maximum value, and finally obtain the device parameters for realizing the adjustable beam - splitting ratio function. It should be noted that for the simulation equipment, in addition to the commercial software Ansys Lumerical Mode, other simulation software, equipment or other simulation methods can also be used.

[0055] The thickness of the silicon substrate 400 in this embodiment is 2μm; the material of the buried - oxide layer 500 is silicon dioxide, and the thickness is 3μm; the middle waveguide 200 and the two side waveguides 100 are both ridge - type silicon waveguides, and the bottom - layer silicon thickness is 90nm, and the ridge - type silicon waveguide thickness is 130nm. Through simulation optimization, the spacing between the waveguides is 405nm, the width of the middle waveguide 200 is 438.1nm, and the width of the two side waveguides 100 is 500nm; the phase - change material 300 is a Sb2Se3 phase - change material layer, and the thickness in the amorphous state is 30nm. Through experimental verification, its thickness changes with the degree of crystallization, and the formula is: where is the thickness value of the phase change material with different crystallization degrees, is the thickness value of the non-crystallized phase change material, is the crystallization degree of the phase change material; the protective layer 600 is made of alumina material, wrapping the entire device surface with a thickness of 40 nm. Among them, the thickness of the silicon substrate 400, the buried oxide layer 500, the middle waveguide 200 and the two side waveguides 100 are determined by the specifications of the used SOI substrate. All other device structure values are the optimal ideal values obtained after multiple optimizations and simulations. After using the model simulated and designed in software mode, when in the crystalline state, the refractive index of the material is 4.3671 and the coupling length is 49.2697 μm; when in the amorphous state, the refractive index of the material is 3.4764, Figure 3 The effective refractive index of the symmetric mode one of , Figure 4 The effective refractive index of the antisymmetric mode of , Figure 5 The effective refractive index of the symmetric mode 2 of , calculated to obtain , and the coupling length is 24.7176 μm. At this time, it approximately satisfies that the effective refractive indices of the three supermodes in the amorphous state form an arithmetic progression, which can make the coupling efficiency of the three-waveguide directional coupler reach the maximum as much as possible, and also satisfies the relationship that the coupling length in the crystalline state is twice that in the amorphous state, enabling the dynamic regulation function.

[0056] Embodiment 3 As Figure 6 shown, the embodiment of the present invention provides a method for dynamically regulating the splitting ratio of a beam splitter, including: Covering a phase change material on the optical waveguide of the directional coupler of the beam splitter; By controlling the phase change degree of the phase change material, making the phase change material in different phase change states to perform dynamic regulation of the splitting ratio, wherein the phase change states include a crystalline state, an amorphous state and several intermediate states, and the intermediate states are states between the amorphous state and the crystalline state.

[0057] The regulation method of this embodiment changes the effective refractive index of the optical waveguide by changing the phase change state of the phase change material covered on the optical waveguide of the directional coupler, and further changes the final splitting ratio of the beam splitter. The phase change states of the phase change material include not only the crystalline state and the amorphous state, but also intermediate states between the crystalline state and the amorphous state. The regulation method of this embodiment utilizes multiple phase change states of the phase change material to achieve multiple splitting ratios. Compared with only using the crystalline state and the amorphous state to have two splitting ratios, the regulation method of this embodiment can achieve three or more splitting ratios and can change the splitting ratio during use.

[0058] Specifically, the directional coupler of this embodiment is as Figure 1 and Figure 2As shown in the figure, the directional coupler of this embodiment adopts a three-waveguide directional coupler. The middle region of the directional coupler is a coupling region composed of two ridge-type silicon waveguides and a hybrid ridge-type silicon waveguide. The spacing between the three waveguides is very small, enabling waveguide-to-waveguide coupling. On the left and right sides, two ridge-type silicon waveguides extend to form the input waveguide 700 and the output waveguide 800 respectively. The spacing between the two ridge waveguides is relatively large, effectively avoiding waveguide-to-waveguide coupling. When light is input from one waveguide, the output waveguide 800 on the same side is set as the Bar port, and the output waveguide 800 on the opposite side is set as the Cross port.

[0059] Moreover, the phase change material of this embodiment adopts Sb2Se3. The phase change of Sb2Se3 is the transformation between the crystalline state and the amorphous state. Therefore, the phase change of Sb2Se3 is also called crystallization. The crystallization of the phase change material Sb2Se3 proceeds step by step. Before complete crystallization, there are intermediate states between the amorphous state and the crystalline state. Due to its non-volatile characteristics, these intermediate states can also exist stably. Therefore, during the crystallization process, multiple intermediate states can be obtained through external stimuli, which is conducive to achieving continuous control in dynamic regulation, that is, quasi-continuous regulation.

[0060] Furthermore, by controlling the degree of the phase change material to make the phase change material in different phase change states, it includes: changing the phase change state of the phase change material by thermal control, optical control or electrical control. The phase change state of the phase change material is changed through external stimuli. The phase change material Sb2Se3 of this embodiment can change its phase change state by means such as thermal control, optical control or electrical control. Specifically, external thermal control, optical control or electrical control and other regulation devices are used to control and change the phase change state of the phase change material.

[0061] Even further, by controlling the phase change degree of the phase change material to make the phase change material in different phase change states, the dynamic regulation of the splitting ratio is carried out to determine the required splitting ratio; Obtain the coupling power ratio diagram of the output ports of the beam splitter with different phase change degrees; According to the required splitting ratio and the coupling power ratio diagram, obtain the required phase change degree of the phase change material; Determine the regulation parameters according to the required phase change degree of the phase change material; Apply external stimuli to the phase change material according to the regulation parameters.

[0062] Obtaining the coupling power ratio diagram of the output ports of the beam splitter with different phase change degrees includes: Obtain the geometric parameters and material parameters of the directional coupler; among them, the geometric parameters of the directional coupler mainly include the optical waveguide spacing and the coupling region length; According to the geometric parameters and material parameters of the directional coupler, obtain the coupling power ratio diagram of the output ports of the beam splitter with different phase change degrees.

[0063] In applying an external stimulus to the phase-change material according to the regulation parameters, the degree of phase change of the phase-change material is obtained by measuring the dielectric constant of the phase-change material.

[0064] The regulation method of this embodiment is applicable to the device design stage or the usage stage after the device is finished. In the device design stage, the geometric parameters of the directional coupler are initially set, simulated and optimized, the optical waveguide spacing and the coupling region length are determined to meet the design conditions, and then the coupling power ratio diagram of the output ports of the beam splitter with different phase change degrees is obtained through simulation, so as to determine the degree of phase change of the phase-change material corresponding to the splitting ratio, output the final design parameters of the device and the degree of phase change of the phase-change material corresponding to the splitting ratio, and finally apply an external stimulus to the designed device according to the degree of phase change of the phase-change material corresponding to the splitting ratio. In the device usage stage, according to the corresponding relationship between the splitting ratio obtained in the design stage and the degree of phase change of the phase-change material, the initial adjustment parameters are obtained, an external stimulus is applied to the phase-change material for adjustment, and the parameters of the external stimulus are gradually adjusted until the desired splitting ratio is obtained. In this embodiment, how to obtain the desired splitting ratio, that is, to obtain the final regulation parameters, is provided, including: S1. Determine the required splitting ratio; S2. Obtain the geometric parameters and material parameters of the directional coupler; S3. Obtain the coupling power ratio diagram of the output ports of the beam splitter with different phase change degrees according to the geometric parameters and material parameters of the directional coupler; S4. Obtain the required degree of phase change of the phase-change material according to the required splitting ratio and the coupling power ratio diagram; S5. Determine the regulation parameters according to the required degree of phase change of the phase-change material; S6. Apply an external stimulus to the phase-change material according to the regulation parameters; S7. Measure the dielectric constant of the phase-change material, and judge whether the phase-change material reaches the phase change state obtained in step S4 according to the dielectric constant. If so, end the regulation. If not, modify the regulation parameters until the corresponding phase change state is reached.

[0065] In step S7, since the crystallization process of the phase-change material is continuous, during the regulation process, if the phase change state does not reach the required degree, the external stimulus is increased. In step S6, when applying the external stimulus, first use a value less than the regulation parameter obtained in step S7, and then gradually increase it.

[0066] In step S7, measure the dielectric constant of the phase-change material. Among them, the dielectric constant of the intermediate state with different crystallization degrees can be obtained through the Lorentz relation formula:

[0067] Among them, represents the crystallization degree, is the amorphous state, is crystalline, is the effective dielectric constant of the intermediate state of Sb2Se3, is the wavelength, is the effective dielectric constant of the amorphous state of Sb2Se3, is the effective dielectric constant of the fully crystalline state of Sb2Se3. After obtaining the dielectric constants of the intermediate states with different degrees of crystallization according to the above formula, the performance of different states can be further studied.

[0068] According to the coupled-mode theory, the optical power transmission characteristics of the directional coupler are calculated by the following formula, and the power component transferred from the input waveguide to the output waveguide at a certain coupling length of light is obtained:

[0069] where L represents the length of the coupling region of the device, that is, the length of the coupling region between waveguides; is the complete coupling length constant of the device under different phase transition degrees, that is, it represents when there is a phase difference between two modes, the specific length required for light to be completely coupled from one waveguide to another waveguide.

[0070] When the phase change material Sb2Se3 is in the amorphous state , when the phase change material Sb2Se3 is in the crystalline state , according to the calculation formula of the output power component of the directional coupler, the optical power ratio of the Cross and Bar ports in the crystalline state can be obtained as Figure 7 shown and the optical power ratio of the Cross and Bar ports in the amorphous state as Figure 8 shown in the curve graph. Taking the coupling length in the crystalline state as the fixed coupling region length L of the device, intersecting with the curve at two points, the splitting ratio in different states can be obtained. When the phase change material Sb2Se3 is in the crystalline state, that is, m = 1, due to the increase in the refractive index of the material, the phase matching of the three supermodes is not satisfied, and the device coupling region length L is equal to the complete coupling length constant , the phase difference between the modes is , and the optical power is completely coupled to the opposite waveguide, so it is output from the Cross port. From Figure 7 , it can be seen that the optical power ratio of the output ports Cross port and Bar port is 1:0; when the phase change material Sb2Se3 is in the amorphous state, at this time the phase matching of the three supermodes is satisfied, but the device coupling region length L is twice the complete coupling length in the amorphous state. The phase difference between the modes is which causes the optical power to be completely coupled to the opposite waveguide and then completely coupled back to the same-side waveguide from the opposite waveguide, and finally output from the Bar port. From Figure 8 , it can be seen that the optical power ratio of the output ports Cross port and Bar port is 0:1.

[0071] The crystallization process of Sb2Se3 is accompanied by the growth of crystal nuclei, and continuous heating is required to be more conducive to crystallization. The transition from the crystalline state to the amorphous state requires a temperature higher than the melting temperature of the material and a process of rapid cooling. Changing the parameters of the corresponding external stimulation method can regulate the crystallization degree of the phase change material Sb2Se3, thereby realizing the function of dynamically regulating the splitting ratio. The coupling region length of the device , when the crystallization degree of the material is such that the refractive index of the material is 3.59118 and the coupling length is 27.3363 μm, after the optical power is completely coupled to the opposite waveguide, a small part of the light is coupled back to the same-side waveguide for output. The optical power ratios of the Cross and Bar ports are as Figure 9 shown. The optical power ratio of the Cross port to the Bar port is 0.09:0.91, approximately 1:9. When the crystallization degree of the material is such that the refractive index is 3.6692 and the coupling length is 28.923 μm, after the optical power is completely coupled to the opposite waveguide, a small part of the light is coupled back to the same-side waveguide for output. The optical power ratios of the Cross and Bar ports are as Figure 10 shown, and the ratio is 2:8. When the crystallization degree of the material is such that the refractive index is 3.83872 and the coupling length is 32.8264 μm, after the optical power is completely coupled to the opposite waveguide, half of the light is coupled back to the same-side waveguide for output. The optical power ratios of the Cross and Bar ports are as Figure 11 shown. The optical power ratio of the Cross port to the Bar port is 5:5. When the crystallization degree of the material is such that the refractive index is 4.02949 and the coupling length is 38.0179 μm, after the optical power is completely coupled to the opposite waveguide, most of the light is coupled back to the same-side waveguide for output. The optical power ratios of the Cross and Bar ports are as Figure 12 shown. The optical power ratio of the Cross port to the Bar port is 8:2. When the crystallization degree of the material is such that the refractive index is 4.13437 and the coupling length is 41.2526 μm, after the optical power is completely coupled to the opposite waveguide, most of the light is coupled back to the same-side waveguide for output. The optical power ratios of the Cross and Bar ports are as Figure 13 shown. The optical power ratio of the Cross port to the Bar port is 0.91:0.09, approximately 9:1. It can be seen from this that by regulating the state of the phase change material, this technology can achieve a dynamically adjustable splitting ratio. Figure 14It shows the splitting ratio of the output ports corresponding to different crystallization degrees of Sb2Se3. The coupling power ratio between the Cross port and the Bar port can change dynamically as the crystallization degree varies from m = 0 to m = 1, continuously changing from 0:1 to 1:0. It can be intuitively seen that by adjusting the crystallization degree of the phase change material Sb2Se3, the splitting ratio of the three-waveguide directional coupler splitter can be dynamically adjusted.

[0072] In summary, the embodiment of the present invention provides a splitter, which includes a directional coupler and a regulation device. The directional coupler includes an optical waveguide, and a phase change material is covered on the optical waveguide. The regulation device is used to switch the phase change state of the phase change material. The phase change state of the phase change material includes a crystalline state, an amorphous state, and several intermediate states, and the intermediate state is a state between the amorphous state and the crystalline state. The splitter of the embodiment of the present invention changes the phase change state of the phase change material on the optical waveguide of the directional coupler through the regulation device, thereby realizing the dynamic regulation of the splitting ratio. The embodiment of the present invention also provides a method for dynamically regulating the splitting ratio of the splitter, which changes the phase change state of the phase change material on the optical waveguide. By using the crystalline state, the amorphous state, and several intermediate states between the crystalline state and the amorphous state, three or more splitting ratios can be obtained. During the regulation process, the degree of the applied external stimulus is gradually increased to realize the development of the crystallization degree of the phase change material, that is, from the amorphous state to the crystalline state, so that the splitting ratio gradually increases, realizing the dynamic continuous regulation of the splitting ratio. The splitting ratio can be dynamically regulated during use, with higher flexibility and adaptability; the phase change material uses Sb2Se3. Based on the non-volatile characteristics of the Sb2Se3 material, the splitting ratio designed by the splitter of the present invention has stability.

[0073] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and substitutions can be made, and these improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A beam splitter, characterized in that, It includes a directional coupler and a control device. The directional coupler includes an optical waveguide, and a phase change material (300) is covered on the optical waveguide. The control device is used to switch the phase change state of the phase change material (300). Among them, the phase change state of the phase change material (300) includes a crystalline state, an amorphous state, and several intermediate states, and the intermediate state is a state between the amorphous state and the crystalline state.

2. The beam splitter according to claim 1, wherein The control device is a thermal control device, an optical control device or an electrical control device.

3. The beam splitter according to claim 1, wherein The optical waveguide includes two side waveguides (100) and an intermediate waveguide (200). The intermediate waveguide (200) is arranged between the two side waveguides (100), so that the directional coupler is a three-waveguide directional coupler, and the phase change material (300) is arranged on the intermediate waveguide (200).

4. The beam splitter according to claim 3, wherein The coupling region length of the directional coupler is the coupling length required when the phase change material (300) is in the crystalline state, and the coupling length of the phase change material (300) in the crystalline state is twice that in the amorphous state.

5. The beam splitter according to claim 3, characterized in that, The two side waveguides (100) are parallel, such that the directional coupler supports two symmetric modes and one anti-symmetric mode, and the effective refractive indices of the two symmetric modes are respectively and , and the effective refractive index of the anti-symmetric mode is , and the values of the effective refractive indices of the three supermodes satisfy: 。 6. A method for dynamically regulating the splitting ratio of a beam splitter, characterized in that, It includes: Covering a phase change material on the optical waveguide of the directional coupler of the beam splitter; By controlling the phase change degree of the phase change material, making the phase change material in different phase change states, and performing dynamic regulation of the splitting ratio. Among them, the phase change state includes a crystalline state, an amorphous state, and several intermediate states, and the intermediate state is a state between the amorphous state and the crystalline state.

7. The method for dynamically adjusting the splitting ratio of a beam splitter according to claim 6, characterized in that The step of making the phase change material in different phase change states by controlling the phase change degree of the phase change material includes: Changing the phase change state of the phase change material by thermal control, optical control or electrical control.

8. The method for dynamically adjusting the splitting ratio of a beam splitter according to claim 6, wherein The step of performing dynamic regulation of the splitting ratio by making the phase change material in different phase change states by controlling the phase change degree of the phase change material includes: Determining the required splitting ratio; Obtaining the coupling power ratio diagram of the output ports of the beam splitter with different phase change degrees; Obtaining the required phase change degree of the phase change material according to the required splitting ratio and the coupling power ratio diagram; Determining the control parameter according to the required phase change degree of the phase change material; Applying an external stimulus to the phase change material according to the control parameter.

9. The method for dynamically adjusting the splitting ratio of a beam splitter according to claim 8, characterized in that Obtaining the coupling power ratio diagram of the output ports of the beam splitter with different phase change degrees includes: Obtaining the geometric parameters and material parameters of the directional coupler; Obtaining the coupling power ratio diagram of the output ports of the beam splitter with different phase change degrees according to the geometric parameters and material parameters of the directional coupler.

10. The method for dynamically adjusting the splitting ratio of a beam splitter according to claim 8, characterized in that, In the step of applying an external stimulus to the phase change material according to the control parameter, the phase change degree of the phase change material is obtained by measuring the dielectric constant of the phase change material.

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