A mid-infrared phase shifter

Abstract

The application discloses a mid-infrared phase shifter. The phase shifter comprises a substrate, a slab optical waveguide formed on the substrate, a patterned heating layer located on the middle part of the slab optical waveguide, a ridge waveguide formed on the middle part of the slab optical waveguide and the patterned heating layer, two patterned electrodes respectively formed on the two sides of the patterned heating layer, and a cladding layer formed on the ridge waveguide. The mid-infrared light signal is input into the phase shifter through an input waveguide, the graphene is powered to generate heat energy to heat the waveguide through the heating control structure, the refractive index of the waveguide is modulated, and the output phase of the light signal passing through the phase shifter is changed, so that the problem that the traditional silicon-on-insulator device cannot work due to excessive loss in the mid-infrared region is solved.

Description

Technical Field

[0001] This invention relates to a phase-shifting device in the fields of optical communication technology, optical detection technology and lidar, and particularly to a mid-infrared chalcogenide glass / silicon hybrid waveguide phase-shifting device. Background Technology

[0002] Since the beginning of the 21st century, the rapid development of technologies such as the Internet, the Internet of Things (IoT), cloud computing, and big data has led to a dramatic increase in the generation and demand for information, resulting in a year-on-year increase in communication data volume and a continuous rise in bandwidth requirements. On-chip optical interconnects (OSIs), with their advantages of low crosstalk, low latency, high integration, and large capacity, perfectly meet the interconnect technology needs of next-generation data centers and have therefore been extensively researched and reported in recent years. On-chip integrated optical switches are core components of optical switching networks. Compared to traditional MEMS (Micro-Electro-Mechanical System) optical switches, they offer advantages such as smaller size, lower power consumption, no inertia, faster response speed, and higher precision. The core component of an optical switch is the optical phase shifter, making its performance crucial for optical switching networks. Furthermore, the IoT and cloud computing have also promoted the development and prosperity of 3D sensing technology, with lidar being the main hardware structure. Currently, lidar primarily uses mechanical scanning, which is large, slow, and inertial, resulting in low scanning accuracy. Phased array technology is an excellent way to avoid the defects of mechanical structures, and the development of on-chip optical radar has been booming in recent years. Phase shifters are an important component of on-chip integrated optical phased array radar and one of the key ways to achieve phased array radar scanning. Therefore, research on phase shifters is essential. Summary of the Invention

[0003] To address the problem of excessive losses preventing the operation of phase shifters fabricated on the SOI platform in the mid-infrared band, this invention provides a phase shifting device based on a chalcogenide glass / silicon hybrid platform, thereby overcoming the shortcomings of existing technology platforms.

[0004] This invention achieves a highly efficient thermally modulated optical phase shifter by sandwiching graphene between silicon and chalcogenide glass. A transparent heating layer is introduced using a chalcogenide glass / silicon hybrid waveguide structure. Combined with a low-refractive-index chalcogenide cladding, the waveguide is effectively protected from external environmental interference without causing additional optical loss. An electrode lead-out structure isolates the electrodes from the influence of the optical field distribution and facilitates electrical wiring, enabling increased integration of optical networks. By controlling graphene with electrical signals of varying intensities to generate different power to heat the chalcogenide glass / silicon hybrid waveguide, the input optical signal is modulated, thereby changing the phase of the output light from the hybrid waveguide.

[0005] The technical solution adopted in this invention includes:

[0006] Including substrate;

[0007] This includes planar optical waveguides formed on a substrate;

[0008] It includes a patterned heating layer located in the middle of the planar optical waveguide;

[0009] It includes a ridge waveguide, formed between a planar optical waveguide and a patterned heating layer;

[0010] It includes two patterned electrodes, which are formed on both sides of the patterned heating layer;

[0011] Including the cladding, formed on the ridge waveguide.

[0012] The ridge waveguide is located in the upper part of the planar optical waveguide. The chalcogenide cladding is formed on the planar optical waveguide and covers the patterned heating layer, patterned electrodes and ridge waveguide, providing waveguide protection.

[0013] It also includes two patterned electrodes, each connected to an external electrode control circuit via its own electrode lead-out structure.

[0014] The substrate material is a mid-infrared transparent material such as sapphire, calcium fluoride, or magnesium fluoride.

[0015] The flat optical waveguide is made of a thermosensitive material such as silicon.

[0016] The patterned heating layer is made of graphene.

[0017] The patterned electrode can be made of any conductive material, including but not limited to metals.

[0018] The ridge waveguide is made of high-refractive-index chalcogenide glass, where high refractive index means that the refractive index is similar to that of silicon.

[0019] The cladding material is a low-refractive-index chalcogenide glass material, where low refractive index means that the refractive index is less than that of the ridge waveguide.

[0020] The electrode lead-out structure can be made of any conductive material, including but not limited to metals.

[0021] The beneficial effects of this invention are as follows:

[0022] The substrate, waveguide, and cladding materials used in this invention all have transparent windows in the mid-infrared region, thus enabling efficient operation in the mid-infrared. This invention uses graphene as a heating layer, which has no effect on the light field distribution. The design of this invention can isolate the electrodes from the waveguide, thereby reducing the influence of the electrodes on the light field distribution within the waveguide. In addition, the application of the cladding facilitates wiring of large-scale optoelectronic interconnect structures.

[0023] In this invention, a mid-infrared light signal is input to a phase-shifting device via an input waveguide. A heating control structure powers the graphene to generate heat energy that heats the waveguide, modulating the refractive index of the waveguide and thus changing the output phase of the light signal passing through the phase shifter.

[0024] This invention realizes a phase-shifting device in the mid-infrared region, solving the problem that traditional silicon-based devices on insulators cannot work due to excessive losses in the mid-infrared region. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0026] Figure 1 This is a cross-sectional schematic diagram of the present invention.

[0027] Figure 2 This is a process flow diagram of the present invention.

[0028] Figure 3 This is a schematic diagram of a Mach-Zehnder interference optical switch based on a phase shifter.

[0029] Figure 3R This is a schematic diagram of the operation of a Mach-Zehnder interference optical switch based on a phase shifter.

[0030] Figure 4 This is a schematic diagram of a micro-ring filter based on a phase shifter.

[0031] Figure 4R This is a schematic diagram of a micro-ring filter based on a phase shifter.

[0032] Figure 5 This is a schematic diagram of a phased array radar based on a phase shifter.

[0033] To illustrate the device structure more intuitively, Figure 3 , Figure 4 , Figure 5 The optical waveguide is shown through the structural surface; other multilayer structures are not shown. Cross-sectional views of the device are provided. Figure 1 Consistent. Detailed Implementation

[0034] This document will exemplify some embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0035] like Figure 1 As shown, the device structure includes:

[0036] Including substrate 1-1;

[0037] It includes a planar optical waveguide 1-2, which is formed on a substrate 1-1 and integrated with the substrate 1-1 using bonding and other processes;

[0038] It includes a patterned heating layer 1-3, located in the middle of the planar optical waveguide 1-2, which is transferred and fabricated on the planar optical waveguide 1-2;

[0039] Including ridge waveguide 1-5, formed between planar optical waveguide 1-2 and patterned heating layer 1-3, specifically grown on patterned heating layer 1-3 by thermal evaporation;

[0040] It includes two patterned electrodes 1-4, which are formed on both sides of the patterned heating layer 1-3, respectively;

[0041] It includes cladding 1-6, which is formed on ridge waveguide 1-5. The cladding covers and protects the patterned heating layer 1-3, patterned electrode 1-4 and ridge waveguide 1-5. Specifically, it is grown on ridge waveguide 1-5 by thermal evaporation.

[0042] The ridge waveguide 1-5 is located on the top of the middle part of the planar optical waveguide. The chalcogenide cladding is formed on the planar optical waveguide 1-2. Specifically, it is grown on the planar optical waveguide 1-2 by thermal evaporation and covers the patterned heating layer 1-3, the patterned electrode 1-4 and the ridge waveguide 1-5 to provide waveguide protection.

[0043] It also includes two patterned electrodes 1-4, each connected to an external electrode control circuit 1-8 via its own electrode lead-out structure 1-7. The electrode control circuit 1-8 is disposed on the cladding to prevent it from affecting the optical field distribution within the waveguide. The electrode control circuit 1-8 is connected to the electrode below through the electrode lead-out structure 1-7 within a through-hole, forming an electrical control structure. Specifically, the electrode lead-out structure 1-7 is fabricated within the cladding 1-6, passes through the cladding 1-6, and connects to the patterned electrode 1-4.

[0044] An electrical control structure is composed of patterned electrodes 1-4, electrode lead-out structures 1-7, and electrode control circuits 1-8. Optical signals are input through a signal input waveguide to a hybrid ridge waveguide composed of planar optical waveguide 1-2 and ridge waveguide 1-5. The electrical control structure electrically controls the heating layer 1-3, causing it to generate different thermal powers to heat the hybrid ridge waveguide composed of planar optical waveguide 1-2 and ridge waveguide 1-5. This changes the equivalent refractive index of the hybrid ridge waveguide, thereby regulating the output phase of the phase shifter's output optical signal.

[0045] In this structure, the patterned heating layer 1-3 is located between the ridge waveguide 1-5 and the planar optical waveguide 1-2, which makes the patterned heating layer 1-3 have a shorter heat conduction distance, higher heating efficiency, and does not affect the optical field distribution in the hybrid waveguide.

[0046] This invention improves heating efficiency and does not affect the optical field within the hybrid waveguide by placing patterned heating layers 1-3 inside the hybrid waveguide and achieving phase-shift modulation at the middle position.

[0047] In specific implementation, the preparation process is as follows: Figure 2 A single-crystal silicon layer of suitable thickness 2-2 is grown on a sapphire substrate 2-1 via epitaxial growth. Then, graphene 2-3 is transferred to the silicon surface and patterned. Subsequently, electrodes 2-4 are fabricated at specific locations on the patterned graphene. High-refractive-index chalcogenide glass is deposited and patterned into a ridge waveguide 2-5. Low-refractive-index chalcogenide material 2-6 is deposited and vias 2-7 are etched to fabricate via connection structures and surface circuits 2-8.

[0048] Example 1

[0049] Mach-Zehnder interference optical switch, see Figure 3 .

[0050] The optical signal is input from the input waveguide 3-1 and split into beams in the multimode interferometer 3-2. One beam passes through a conventional waveguide and enters the 2x2 multimode interferometer 3-3, while the other passes through a phase shifter 3-4 and enters the multimode interferometer. Different voltage amplitudes are applied to the graphene heating layer in the phase shifter via circuit structure 3-5 to change its heating power, thereby achieving phase modulation of the optical wave in the optical waveguide. Different voltages applied to the graphene generate different heating temperatures, thus changing the phase of the output optical wave from the phase shifter. This allows for precise control of the phase difference between the two arms of the Mach-Zehnder waveguide, ultimately enabling the optical signal to be switched on and off at the output port. Figure 3R As shown, by changing the phase shifter voltage to V1 at time a, the Mach-Zehnder optical switch can be changed from the on state to the off state.

[0051] Example 2

[0052] Adjustable micro-loop filter, see Figure 4 .

[0053] An optical signal is input from the straight waveguide 4-1. When the optical path length in the micro-ring 4-2 satisfies constructive interference, the light will be output from the other end of the straight waveguide. When the optical path length in the micro-ring satisfies destructive interference, there is no optical signal output from the straight waveguide. A phase shifter 4-3 is introduced inside the micro-ring. Different voltages are applied to the graphene heating layer in the phase shifter through circuit structure 4-4, thereby changing its heating power and modulating the refractive index of the chalcogenide glass / silicon hybrid waveguide. This changes the optical path length in the micro-ring, and consequently, alters whether there is a signal output at the straight waveguide output port, achieving filtering of light of different wavelengths. Figure 4R As shown, changing the phase shifter voltage can change the optical output of the micro-ring resonator to achieve the filtering function.

[0054] Example 3

[0055] Optical phased array radar, see Figure 5 .

[0056] The optical signal is input from the input waveguide 5-1 to the multimode interferometer 5-2 for cascaded beam splitting. Each beam after splitting is input to the phase shifter 5-3. Different voltages are applied to the graphene heating layer in the phase shifter through circuit structure 5-4, thereby changing its thermal power and modulating the refractive index of the chalcogenide glass / silicon hybrid waveguide, thus changing the phase in each path. By controlling the output phase in each waveguide through the phase shifter to form a specific phase gradient, and then coupling it into free space through the coupling grating 5-5, the phased array scanning function can be realized.

[0057] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” used in this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to any and all possible combinations comprising one or more of the associated listed items.

Claims

1. A mid-infrared phase shifter, characterized in that: Including substrate (1-1); It includes a planar optical waveguide (1-2) formed on a substrate (1-1); It includes a patterned heating layer (1-3), located in the middle of the planar optical waveguide (1-2); It includes a ridge waveguide (1-5) formed between the planar optical waveguide (1-2) and the patterned heating layer (1-3); It includes two patterned electrodes (1-4), which are formed on both sides of the patterned heating layer (1-3); The two patterned electrodes (1-4) are at the same height as the bottom of the ridge waveguide (1-5) and are lower than the protrusion of the ridge waveguide (1-5); Includes cladding (1-6), formed on the ridge waveguide (1-5); The ridge waveguide (1-5) is made of high-refractive-index chalcogenide glass, where high refractive index means that the refractive index is similar to that of silicon. The cladding (1-6) is made of low-refractive-index chalcogenide glass, where low refractive index means that the refractive index is less than that of the ridge waveguide (1-5). It also includes two patterned electrodes (1-4), each of which is connected to an external electrode control circuit (1-8) via its own electrode lead-out structure (1-7); and the upper end of the electrode lead-out structure (1-7) is flush with the cladding (1-6), and the upper end of the electrode lead-out structure (1-7) and the electrode control circuit (1-8) are higher than the protrusion of the ridge waveguide (1-5).

2. The mid-infrared phase shifter according to claim 1, characterized in that: The ridge waveguide (1-5) is located on the planar optical waveguide (1-2), and the chalcogenide cladding is formed on the planar optical waveguide (1-2) and covers the patterned heating layer (1-3), the patterned electrode (1-4) and the ridge waveguide (1-5).

3. A mid-infrared phase shifter according to claim 1, characterized in that: The patterned heating layer (1-3) is made of graphene.

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