Tunable optical waveguide device

Abstract

The invention discloses a tunable optical waveguide device, which is characterized in that a tunable hybrid waveguide is formed by horizontally or vertically embedding a phase change material into a waveguide. The phase change material has a plurality of stable and reversible phases, and the phase change material is crystallized, non-crystallized or partially non-crystalline by heating the phase change material. The effective refractive index difference of the mixed waveguide interference arm of the phase change material in different crystal phases is large, the pi phase shift can be realized under the action length of the waveguide interference arm in micron dimension, and the length of the waveguide interference arm is reduced by 3-4 orders of magnitude, so that the size of the device is reduced, and the power consumption of the device is reduced. The phase difference of the two waveguide interference arms is realized by setting the two waveguide interference arms as a symmetrical structure or an asymmetric structure and changing the crystal phase of the phase-change material film, so that the functions of an optical switch, a tunable optical coupler and a tunable optical filter are realized. The method can be widely applied to an optical neural network, an optical calculation network and an optical delay network which do not need to frequently change switch states and tune phases.

Description

Technical Field

[0001] The present invention relates to an optical waveguide device, and more particularly to a tunable optical waveguide device. Background Art

[0002] With the rapid development of photonic integrated circuits, optical tunable devices, such as optical switches, tunable phase shifters, and tunable couplers, make the system more flexible and are widely used in optical computing, optical neural networks, photonic storage, and data centers. In these application areas, the optical switch state does not need to be switched frequently. Compared with the switching speed, power consumption and device size are more important. In general, tunable units usually rely on weak tuning mechanisms, such as thermo-optical effect and electro-optical effect. These weak tuning mechanisms provide small refractive index changes and often require a larger action length to achieve the required phase change, which limits the tuning range and scalability of the optical tuning unit, resulting in larger device size and higher energy consumption. When multiple tunable optical waveguide devices are required in the system, high energy consumption can easily cause thermal crosstalk to the system, affecting the performance of the system, requiring a more complex compensation mechanism. Non-volatile materials, such as Sb2Se3 and Sb2S3, have significantly different refractive indices in the crystalline and amorphous states. They are stable and reversible in the crystalline, amorphous, and partially amorphous states. Once the phase change is completed, they do not require continuous power supply. These materials help to realize stable optical switches and adjustable beam splitters in the non-volatile state, and can solve the thermal crosstalk problem caused by high energy consumption while maintaining a compact structure. Summary of the invention

[0003] In view of the deficiencies of the prior art, the present invention provides a tunable optical waveguide device.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A tunable optical waveguide device comprises an input optical waveguide, a waveguide beam splitter I, a waveguide interference arm, a waveguide beam splitter II and an output optical waveguide connected in sequence, wherein a phase change material film is horizontally or vertically embedded in a waveguide core layer of the waveguide interference arm to form a hybrid waveguide;

[0006] The phase difference between the two waveguide interference arms is achieved by setting the two waveguide interference arms to be a symmetrical structure or an asymmetrical structure and changing the crystal phase of the phase change material film, thereby realizing the functions of an optical switch, a tunable optical coupler and a tunable optical filter.

[0007] Furthermore, a heating electrode is arranged above the upper cladding of the hybrid waveguide, and the crystal phase of the phase change material is changed by the heating electrode, thereby changing the phase difference between the waveguide interference arms.

[0008] Further, the input waveguide and the output waveguide are grating couplers, or inverted cone couplers, or a combination of a cone waveguide and a straight waveguide, or a straight waveguide; and when the input waveguide and the output waveguide are inverted cone couplers, or a combination of a cone waveguide and a straight waveguide, or a straight waveguide, the input waveguide and the output waveguide both need to be coupled to the optical fiber array, and the input channel spacing is set to 127 μm or 250 μm, and the output channel spacing is set to 127 μm or 250 μm.

[0009] Furthermore, the waveguide beam splitter I and the waveguide beam splitter II are both 2×2 3 dB couplers, or both are 2×2 multimode interferometer structures; or, the waveguide beam splitter I is a 1×2 multimode interferometer structure, and the waveguide beam splitter II is a 2×2 multimode interferometer structure.

[0010] Furthermore, the waveguide core layer is a silicon waveguide, or a lithium niobate waveguide, or a silicon nitride waveguide, or a silicon oxynitride waveguide, or a polymer waveguide, or a III-V group waveguide.

[0011] Furthermore, the phase change material is antimony selenide, antimony trisulfide, germanium antimony telluride, germanium antimony selenium telluride, or vanadium dioxide.

[0012] Furthermore, for all the waveguides in the tunable optical waveguide device, when the refractive index of the substrate is less than the refractive index of the core layer, from bottom to top, the waveguides include a substrate, a lower cladding layer, a core layer, and an upper cladding layer, or from bottom to top, the waveguides include a substrate, a lower cladding layer, a core layer, and an upper cladding layer; when the refractive index of the substrate is not less than the refractive index of the core layer, from bottom to top, the waveguides include a substrate, a lower cladding layer, a core layer, and an upper cladding layer; and the refractive indexes of the upper cladding layer and the lower cladding layer are less than the refractive index of the core layer.

[0013] Further, the phase change material film is embedded in the waveguide by any of the following methods:

[0014] (1) Using high-precision photolithography technology to define the directional coupler waveguide and the air slot on the directional coupler waveguide; etching the waveguide to the required depth by dry etching, thereby forming a waveguide with an air slot; using a photoresist pattern to define the air slot; depositing a layer of phase change material film so that the air slot is completely filled with the phase change material, and removing the excess phase change material on the photoresist outside the air slot by a wet stripping process; sputtering a layer of oxide film on the upper surface of the waveguide as an upper cladding layer;

[0015] (2) After the waveguide is manufactured, a window is opened in the upper cladding layer of the waveguide by photolithography and etching, and an air slot with a length of micrometers is etched in the core layer of the waveguide through the window. The air slot is defined by a photoresist pattern, and a phase change material is deposited inside the air slot until the air slot is filled with the phase change material; the phase change material outside the air slot is removed by a wet stripping process; and a layer of oxide film is deposited on the phase change material by a deposition method to protect the phase change material film.

[0016] Furthermore, by setting the two waveguide interference arms to be a symmetrical structure or an asymmetrical structure and changing the phase state of the phase change material film to achieve the phase difference between the two waveguide interference arms, the functions of the optical switch, the tunable optical coupler and the tunable optical filter are realized, specifically:

[0017] By setting two phase change material films to different widths and lengths, or setting two waveguide interference arms 3 to different lengths, an asymmetric waveguide interference arm is formed, and the function of the filter is realized by tuning the phase difference introduced by the asymmetric waveguide interference arm, and the function of the tunable optical filter is realized by changing the ratio of the crystalline phase to the amorphous phase in the phase change material;

[0018] If the waveguide interference arm is a symmetrical structure, the function of the tunable optical coupler is achieved by continuously tuning the ratio of the crystalline state to the amorphous state in the phase change material film of one of the waveguide interference arms;

[0019] If the waveguide interference arms are of symmetrical structure, the phase difference between the two waveguide interference arms can be changed by changing the phase state of the phase change material of one of the waveguide interference arms, thereby realizing the function of optical switch.

[0020] Furthermore, the tunable optical waveguide devices are cascaded and connected alternately with waveguide pairs of unequal lengths to realize the function of a discrete tunable delay line.

[0021] The technical solution provided by the embodiments of the present application may have the following beneficial effects:

[0022] The tunable optical waveguide device of the present invention, the hybrid waveguide is composed of a phase change material film and a waveguide. The phase change material film is embedded in the waveguide core layer, and can be embedded in the waveguide core layer horizontally or vertically to form a hybrid waveguide. In different phases, the effective refractive index of the hybrid waveguide changes greatly, and a larger phase shift is achieved at a shorter action length (micrometer level), which reduces the size and power consumption. After the phase state of the phase change material film is completed, it does not need to be continuously powered to maintain the state and achieve zero static power. By setting the two waveguide interference arms to a symmetrical structure or an asymmetrical structure, and changing the crystal phase of the phase change material film to achieve the phase difference between the two waveguide interference arms, the functions of the optical switch, tunable optical coupler, and tunable optical filter are realized. It has significant advantages in optical neural networks and photon storage in the use scenarios of a large number of tunable optical waveguide devices, avoiding thermal crosstalk caused by a large number of switching operations of the system, and avoiding more complex compensation of the system.

[0023] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0025] Figure 1 Schematic diagram of a tunable optical waveguide device (optical switch) including two 2×2 3 dB couplers.

[0026] Figure 2 Schematic diagram of the cross section of the waveguide interferometer arm.

[0027] Figure 3 A schematic diagram of a tunable optical waveguide device (optical switch) including two 2×2 MMI (Multimode Interference) structures.

[0028] Figure 4 A schematic diagram of a tunable optical waveguide device (optical switch) including a 1×2 MMI structure and a 2×2 MMI structure.

[0029] Figure 5 Schematic diagram of another tunable optical waveguide device (optical switch) including two 2×2 MMI structures.

[0030] Figure 6 Schematic diagram of a tunable optical waveguide device with asymmetric waveguide interference arms (waveguide interference arms have different lengths).

[0031] Figure 7Schematic diagram of a tunable optical waveguide device with asymmetric waveguide interference arms (different lengths of phase change material films).

[0032] Among them: 1 is the input optical waveguide; 2 is the 3 dB coupler; 3 is the waveguide interference arm; 4 is the 2×2 MMI structure; 5 is the 1×2 MMI structure; 6 is the output optical waveguide; 3-1 is the substrate; 3-2 is the lower cladding; 3-3 is the core layer; 3-4 is the phase change material film; 3-5 is the upper cladding; 3-6 is the heating electrode; 9 is the bent waveguide. DETAILED DESCRIPTION

[0033] Here, exemplary embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application.

[0034] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0035] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0036] The tunability of optical waveguide devices usually relies on weak tuning mechanisms, such as electro-optical effect, thermo-optical effect, etc., which requires a longer action length to achieve the corresponding phase change, resulting in the tunable optical waveguide device having a larger size and higher power consumption, which in turn affects the scalability of the system. At the same time, it is easy to cause thermal crosstalk in the system, which requires a more complex tuning mechanism to compensate. Tunable optical waveguide devices make the system more flexible. When tunable optical waveguide devices are used in optical neural networks, optical computing, and optical delay networks, there is no need to frequently switch the switch state and tune the phase. Low power consumption and compact structure are crucial for the reconfigurability and scalability of the system.

[0037] Based on this, Figure 1 , Figure 2As shown, the present application provides a tunable optical waveguide device based on MZI (Mach–Zehnder interferometers), including an input optical waveguide 1, a waveguide beam splitter I, a waveguide interference arm 3, a waveguide beam splitter II and an output optical waveguide 6 connected in sequence, and a phase change material film 3-4 is horizontally or vertically embedded in the waveguide core layer 3-3 of the waveguide interference arm 3 to form a hybrid waveguide; by setting the two waveguide interference arms to a symmetrical structure or an asymmetrical structure, and by changing the phase state of the phase change material film 3-4, the phase difference between the two waveguide interference arms 3 is achieved, thereby realizing the functions of an optical switch, a tunable optical coupler, and a tunable optical filter.

[0038] In a specific implementation, horizontal embedding means that the phase change material film 3-4 is laid flat in the middle of the waveguide and can be parallel to the upper and lower surfaces of the waveguide; vertical embedding means that the phase change material film 3-4 is vertically embedded in the waveguide and can be parallel to the side wall of the waveguide without considering the waveguide etching tilt angle. In actual operation, the side wall and the tilt angle of the groove formed by waveguide etching are determined by the actual process conditions, usually 0-25°.

[0039] The length of the hybrid waveguide can be in the order of micrometers, and a heating electrode 3-6 is arranged above the upper cladding 3-5 thereof. The heating electrode 3-6 changes the phase of the phase change material, thereby changing the phase difference between the waveguide interference arms 3.

[0040] Specifically, the input waveguide and the output waveguide are grating couplers, or inverted cone couplers, or a combination of a cone waveguide and a straight waveguide, or a straight waveguide. When the input waveguide and the output waveguide are inverted cone couplers, or a combination of a cone waveguide and a straight waveguide, or a straight waveguide, if both the input waveguide and the output waveguide need to be coupled with the optical fiber array, the input channel spacing is set to 127 μm or 250 μm, and the output channel spacing is set to 127 μm or 250 μm according to actual conditions.

[0041] In one embodiment, the waveguide beam splitter I and the waveguide beam splitter II are both 2×2 3 dB couplers 2, or both are 2×2 MMI structures 4; in another embodiment, the waveguide beam splitter I may be a 1×2 MMI structure 5, and the waveguide beam splitter II may be a 2×2 MMI structure 4.

[0042] like Figure 1As shown, the tunable optical waveguide device (optical switch) adopts a Mach-Zehnder interferometer (MZI) structure, including two 3 dB couplers and two waveguide interference arms 3. The input optical waveguide 1 and the 3 dB coupler 2, the 3 dB coupler 2 and the waveguide interference arm 3, and the 3 dB coupler 2 and the output optical waveguide 6 are all connected through a curved waveguide 9. The refractive index of the hybrid waveguide is changed by tuning the phase state of the phase change material on the waveguide interference arm 3, thereby changing the phase of the interference arm. By using the MZI interference effect, the optical signal is switched between the two output optical waveguides 6 by changing the phase difference between the two waveguide interference arms 3. When the phase difference between the two waveguide interference arms 3 is 0, the optical signal is output directly, and when the phase difference between the two waveguide interference arms 3 is π, the optical signal is output crosswise. The specific working process is as follows: Assuming that the optical signal is input from one port of the input optical waveguide 1, it passes through the 3 dB coupler 2 and is evenly divided into two beams of light and enters the two waveguide interference arms 3. Assuming that the size and crystal phase of the phase change material film 3-4 on the two arms are consistent, the phase difference generated by the two arms is zero, and then enters another 3 dB coupler 2, and is output from the cross port at the output end. If the initial state of the two arms is amorphous, by applying a voltage to the graphene electrode on one of the waveguide interference arms 3, the hybrid waveguide under the electrode is heated. When heated to a certain temperature, the phase change material crystallizes, and the voltage on the graphene electrode is removed. At this time, the phase difference generated by the two waveguide interference arms 3 is π, and the optical signal is output from the upper port of the output end after passing through the waveguide interference arm 3, and the optical signal has switched its path. When the other amorphous waveguide interference arm 3 is heated to the crystallized state, the phase difference generated by the two waveguide interference arms 3 is 0, and the optical signal has switched its path. The optical path can be repeatedly operated from the crystalline state to the amorphous state, and has reversibility and stability.

[0043] like Figure 3 As shown, Figure 1 The difference in structure is that the MZI structure includes two 2×2 multimode interferometers (MMI) and a pair of waveguide interference arms 3. The input optical waveguide 1 and the 2×2 MMI structure 4, the 2×2 MMI structure 4 and the waveguide interference arm 3, and the 2×2 MMI structure 4 and the output optical waveguide 6 are all connected through a curved waveguide 9. The optical signal is input from one of the channels in the input optical waveguide 1, enters the 2×2 MMI structure 4 through the curved waveguide 9, and is divided into two beams by the 2×2 MMI structure 4 and enters the two waveguide interference arms 3. By tuning the phase state of the phase change material on the waveguide interference arm 3, the refractive index of the hybrid waveguide is changed, and then the phase of the interference arm is changed, thereby controlling the intensity distribution of light at the two output ports, thereby realizing the function of the optical switch.

[0044] like Figure 4As shown, the device includes a 1×2 MMI structure 5, a 2×2 MMI structure 4 and a pair of waveguide interference arms 3. The 1×2 MMI structure 5 and the waveguide interference arm 3, the waveguide interference arm 3 and the 2×2 MMI structure 4, and the 2×2 MMI structure 4 and the output optical waveguide 6 are all connected through a curved waveguide 9. The optical signal is input from the input optical waveguide 1, divided into two beams by the 1×2 MMI structure 5 and enters the two waveguide interference arms 3. By tuning the phase state of the phase change material on one of the arms, the refractive index of the interference arm is changed, thereby realizing the change of the phase difference between the two interference arms, controlling the intensity distribution of the light at the two output ports, and realizing the optical switch function.

[0045] like Figure 5 As shown, Figure 3 The difference is that no curved waveguide 9 is introduced between the two 2×2 MMI structures 4 and the waveguide interference arms 3. The distance between the two waveguide interference arms 3 is sub-micron order, but no coupling occurs. Figure 3 While maintaining the same function as the device shown, the size of the device is further reduced.

[0046] Specifically, the waveguide core layer 3 - 3 may be a silicon waveguide, or a lithium niobate waveguide, or a silicon nitride waveguide, or a silicon oxynitride waveguide, or a polymer waveguide, or a III-V group waveguide.

[0047] Specifically, the phase change material may be antimony selenide (Sb2Se3), antimony trisulfide (Sb2S3), germanium antimony telluride (Ge2Sb2Te5, GST), germanium antimony selenium telluride (Ge2Sb2Se4Te, GSST) or vanadium dioxide (VO2).

[0048] For all waveguides in the tunable optical waveguide device, when the refractive index of the substrate 3-1 is less than the refractive index of the core layer 3-3, from bottom to top, the waveguides include the substrate 3-1, the lower cladding layer 3-2, the core layer 3-3, and the upper cladding layer 3-5 in sequence, or from bottom to top, the waveguides include the substrate 3-1, the core layer 3-3, and the upper cladding layer 3-5 in sequence; when the refractive index of the substrate 3-1 is not less than the refractive index of the core layer 3-3, from bottom to top, the waveguides include the substrate 3-1, the lower cladding layer 3-2, the core layer 3-3, and the upper cladding layer 3-5 in sequence; the refractive indexes of the upper cladding layer 3-5 and the lower cladding layer 3-2 are less than the refractive index of the core layer 3-3, and according to Maxwell's equations and their boundary conditions, the waveguide total reflection transmission condition can be met.

[0049] In a specific implementation, the phase change material film 3-4 is embedded in the waveguide by any of the following methods:

[0050] (1) Use high-precision photolithography technology to define the directional coupler waveguide and the air slot on the directional coupler waveguide; use dry etching (such as inductively coupled plasma etching) to etch the waveguide to the required depth, so as to obtain a waveguide with an air slot; use the photoresist pattern to define the air slot again; deposit a layer of phase change material film 3-4 so that the air slot is completely filled with phase change material, and remove the excess phase change material on the photoresist outside the air slot through a wet stripping process. At this point, the micrometer-level phase change material film 3-4 is prepared. Then, a layer of oxide film is sputtered on the upper surface of the waveguide as an upper cladding layer 3-5 to protect the phase change material from volatilization, and at the same time to reduce the overlapping area between the electrode and the light field, and reduce the absorption loss of the electrode to the light signal.

[0051] (2) After the waveguide is manufactured, a window is opened in the upper cladding layer 3-5 of the waveguide by photolithography and etching, and an air slot of micrometer length is etched in the waveguide core layer 3-3 through the window. The air slot is defined again by a photoresist pattern, and a phase change material is deposited inside the air slot until the air slot is filled with the phase change material. The phase change material outside the air slot is removed by a wet stripping method. A layer of oxide film is deposited on the phase change material by a deposition method to protect the phase change material film 3-4.

[0052] In a specific implementation, air grooves can be made on both sides of the phase change material during the embedding process, and the power consumption of the device can be further reduced by utilizing the property that the thermal conductivity of air is smaller than the wave conductivity of the material.

[0053] If the heating electrodes 3-6 are graphene electrodes, it is necessary to make metal pins on the chip through coating, photolithography and etching methods, and then make graphene electrodes directly above the hybrid waveguide. When making the graphene electrodes, it is necessary to first transfer the graphene film to the chip, then use acetone to remove the PMMA on the graphene film, and then make the graphene electrodes through photolithography and etching.

[0054] In the tunable optical waveguide device, the phase change material has multiple stable and reversible phases, namely, a crystalline phase, an amorphous phase, and a partially amorphous phase. The phase change material is heated by electrodes to make it crystallized, amorphous, or partially amorphous, thereby changing the phase difference between the two waveguide interference arms 3 and realizing the functions of a tunable coupler and optical signal switching.

[0055] The two waveguide interference arms 3 can be symmetrical or asymmetrical. When the two waveguide interference arms 3 are set to an asymmetrical structure, a non-volatile, compact tunable optical filter and a tunable delay line can be realized; when the two waveguide interference arms 3 are set to a symmetrical waveguide interference arm 3 structure, a low-power, compact, non-volatile optical switch and a tunable coupler can be realized. Specifically, by setting the two phase change material films 3-4 to different widths and lengths, or setting the two waveguide interference arms 3 to different lengths, an asymmetric waveguide interference arm 3 is realized, and by tuning the phase difference introduced by the asymmetric structure, the enhancement or suppression of the optical signal of a specific wavelength is realized to achieve a filtering effect, thereby realizing the function of the filter, and by changing the ratio of the crystalline phase to the amorphous phase in the phase change material, the parameters such as the center wavelength and bandwidth of the filter are changed, thereby realizing the function of tunable filtering; when the waveguide interference arm 3 is a symmetrical structure, the function of the tunable coupler is realized by continuously tuning the ratio of the crystalline state to the amorphous state in the phase change material film 3-4 of one of the waveguide interference arms 3; similarly, when the waveguide interference arm 3 is a symmetrical structure, by changing the phase state of the phase change material film 3-4 of one of the waveguide interference arms 3, the phase difference between the two waveguide interference arms is changed, when the phase difference between the two arms is 0, the optical signal is passed directly, and when the phase difference between the two arms is π, the optical signal crosses, and the function of the optical switch can be realized.

[0056] like Figure 6 As shown, the optical waveguide device is an asymmetric MZI structure, including two 3 dB couplers and two waveguide interference arms 3 of different lengths. The length difference between the two waveguide interference arms 3 is , the optical signal enters the asymmetric MZI, is split into two paths at the 3 dB coupler 2, and enters two interference arms respectively. Due to the asymmetry of the two arms, the optical signal has different transmission paths in the two arms, resulting in different phases accumulated in the two optical signals during the propagation process. At the other 3 dB coupler 2, the two optical signals interfere with each other. The phase difference determines whether the interference is constructive or destructive, thereby affecting the intensity of the output light. By tuning the ratio of the crystalline phase and the amorphous phase of the phase change material in one arm, the effective refractive index of the interference arm is changed, thereby changing the center wavelength of the filter, and finally realizing the function of a tunable filter.

[0057] like Figure 7 As shown, Figure 6The difference is that in this asymmetric MZI, the length of the phase change material in the two arms is different, resulting in different effective refractions in the two arms when the two arms are of the same length. The optical signal is divided into two paths at the 3 dB coupler 2 and enters the two interference arms respectively. Due to the asymmetry of the two arms, the accumulated phases of the optical signal in the two arms are different. At the other 3 dB coupler 2, the two optical signals interfere with each other. The phase difference determines whether the interference is constructive or destructive, thereby affecting the intensity of the output light and realizing the functions of modulation and filtering. By tuning the ratio of the crystalline phase and amorphous phase of the phase change material in one arm, the effective refractive index of the interference arm is changed, thereby changing the center wavelength of the filter, and finally realizing the function of a tunable filter.

[0058] Ordinary tunable optical waveguide devices usually require an action length of millimeters or centimeters to achieve a phase shift of π, and the power consumption is also relatively large. The hybrid waveguide waveguide interference arm 3 of the phase change material in different crystal phases has a large difference in effective refractive index. Under the action length of the waveguide interference arm 3 of the micrometer level, a phase shift of π can be achieved, and the length of the waveguide interference arm 3 is reduced by 3 to 4 orders of magnitude, thereby reducing the size of the device and reducing the power consumption of the device. The low-power optical waveguide device of the present invention can realize the functions of optical switching, optical filtering, and optical delay. The optical waveguide device of the present invention has low power consumption, compact structure, and non-volatility. It is expected to be widely used in optical neural networks, optical waveguide delay lines, and optical computing.

[0059] For tunable optical waveguide devices of cascaded symmetrical MZI structures, connecting them with waveguide pairs of unequal lengths can form discrete tunable delay lines, which have compact structure, low power consumption, non-volatility, and zero static power. This avoids thermal crosstalk on the tunable delay line when a large number of tunable devices are tuned, affecting the performance of the system, and can realize low-power and high-performance tunable delay line devices. The discrete tunable delay line is spiral in shape as a whole and can be integrated on a large scale.

[0060] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the contents disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application.

[0061] It should be understood that the present application is not limited to the exact construction that has been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof.

Claims

1. A tunable optical waveguide device, characterized in that: It includes an input optical waveguide, a waveguide beam splitter I, a waveguide interference arm, a waveguide beam splitter II and an output optical waveguide connected in sequence, and a phase change material film is horizontally or vertically embedded in the waveguide core layer of the waveguide interference arm to form a hybrid waveguide; The two waveguide interference arms are set to a symmetrical structure or an asymmetrical structure, and the phase difference of the two waveguide interference arms is achieved by changing the phase state of the phase change material film, thereby realizing the functions of an optical switch, a tunable optical coupler, and a tunable optical filter.

2. The tunable optical waveguide device according to claim 1, characterized in that: A heating electrode is arranged above the upper cladding of the hybrid waveguide, and the crystal phase of the phase change material is changed by the heating electrode, thereby changing the phase difference between the waveguide interference arms.

3. The tunable optical waveguide device according to claim 1, characterized in that: The input waveguide and the output waveguide are grating couplers, or inverted cone couplers, or a combination of a cone waveguide and a straight waveguide, or a straight waveguide; and when the input waveguide and the output waveguide are inverted cone couplers, or a combination of a cone waveguide and a straight waveguide, or a straight waveguide, the input waveguide and the output waveguide both need to be coupled with an optical fiber array, and the input channel spacing is set to 127 μm or 250 μm, and the output channel spacing is set to 127 μm or 250 μm.

4. The tunable optical waveguide device according to claim 1, characterized in that: The waveguide beam splitter I and the waveguide beam splitter II are both 2×2 3 dB couplers, or both are 2×2 multimode interferometer structures; or, the waveguide beam splitter I is a 1×2 multimode interferometer structure, and the waveguide beam splitter II is a 2×2 multimode interferometer structure.

5. The tunable optical waveguide device according to claim 1, characterized in that: The waveguide core layer is a silicon waveguide, or a lithium niobate waveguide, or a silicon nitride waveguide, or a silicon oxynitride waveguide, or a polymer waveguide, or a III-V group waveguide.

6. The tunable optical waveguide device according to claim 1, characterized in that: The phase change material is antimony selenide, antimony trisulfide, germanium antimony telluride, germanium antimony selenium telluride, or vanadium dioxide.

7. The tunable optical waveguide device according to claim 1, characterized in that: For all the waveguides in the tunable optical waveguide device, when the refractive index of the substrate is less than the refractive index of the core layer, from bottom to top, the waveguides include a substrate, a lower cladding layer, a core layer, and an upper cladding layer, or from bottom to top, the waveguides include a substrate, a core layer, and an upper cladding layer; when the refractive index of the substrate is not less than the refractive index of the core layer, from bottom to top, the waveguides include a substrate, a lower cladding layer, a core layer, and an upper cladding layer; and the refractive indexes of the upper cladding layer and the lower cladding layer are less than the refractive index of the core layer.

8. The tunable optical waveguide device according to claim 1, characterized in that: The phase change material film is embedded in the waveguide by any of the following methods: (1) Using high-precision photolithography technology to define the directional coupler waveguide and the air slot on the directional coupler waveguide; etching the waveguide to the required depth by dry etching to form a waveguide with an air slot; using a photoresist pattern to define the air slot; Depositing a layer of phase change material film so that the air slot is completely filled with the phase change material, removing the excess phase change material on the photoresist outside the air slot by a wet stripping process; sputtering a layer of oxide film on the upper surface of the waveguide as an upper cladding layer; (2) After the waveguide is fabricated, a window is opened in the upper cladding layer of the waveguide by photolithography and etching, and an air slot with a length of micrometers is etched in the core layer of the waveguide through the window. The air slot is defined by a photoresist pattern, and a phase change material is deposited inside the air slot until the air slot is filled with the phase change material. The phase change material outside the air groove is removed by a wet stripping process; an oxide layer film is deposited on the phase change material by a deposition method to protect the phase change material film.

9. The tunable optical waveguide device according to claim 1, characterized in that: By setting the two waveguide interference arms to be a symmetrical structure or an asymmetrical structure and changing the crystal phase of the phase change material film to achieve the phase difference between the two waveguide interference arms, the functions of the optical switch, the tunable optical coupler and the tunable optical filter are realized, specifically: By setting two phase change material films to different widths and lengths, or setting two waveguide interference arms to different lengths, an asymmetric waveguide interference arm is formed, and the filter function is realized by tuning the phase difference introduced by the asymmetric waveguide interference arm, and the function of a tunable optical filter is realized by changing the ratio of the crystalline phase to the amorphous phase in the phase change material; If the waveguide interference arm is a symmetrical structure, the function of the tunable optical coupler is achieved by continuously tuning the ratio of the crystalline state to the amorphous state in the phase change material film of one of the waveguide interference arms; If the waveguide interference arms are of symmetrical structure, the phase difference between the two waveguide interference arms can be changed by changing the phase state of the phase change material of one of the waveguide interference arms, thereby realizing the function of optical switch.

10. The tunable optical waveguide device according to claim 1, characterized in that: The tunable optical waveguide devices are cascaded and connected with waveguide pairs of unequal lengths to realize the function of discrete tunable delay lines.

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