High-speed self-starting silicon light polarization detection device adopting single photoelectric detector

Abstract

The invention discloses a high-speed self-starting silicon light polarization detection device adopting a single photoelectric detector. The high-speed self-starting silicon light polarization detection device comprises a two-dimensional grating coupler, an optical waveguide and a self-starting silicon-based germanium photoelectric detector with a symmetrical energy band structure, the two-dimensional grating coupler is connected with the optical waveguide, and the optical waveguide is connected with two PN junctions of the self-starting silicon-based germanium photoelectric detector with a symmetrical energy band structure; wherein the two-dimensional grating coupler is used for receiving vertical incident light and decomposing the polarization state of the incident light into two orthogonal polarization states, and the light in the two orthogonal polarization states is coupled and transmitted to two PN junctions of the self-starting silicon-based germanium photoelectric detector with a symmetrical energy band structure through the optical waveguide respectively; therefore, the self-starting silicon-based germanium photoelectric detector with the symmetrical energy band structure can generate positive response and negative response. The device is simple in structure, and can be fused with an existing silicon process platform for preparation more easily. Detection of incident light polarization information can be completed only by using one photoelectric detector structure, the utilization rate of the device structure and the density of information contained in an output signal are greatly improved, the system complexity is reduced, the integration degree is improved, the chip area is reduced, and the cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor optoelectronic devices, and in particular to a high-speed self-starting silicon light polarization detection device using a single photodetector. Background Art

[0002] In the past few decades, microelectronics technology with integrated circuits as the core has developed rapidly. However, with the continuous improvement of integration, the size of transistors has continued to shrink, and the inherent capacitance and inductance of the wires in the circuit have limited their transmission speed and bandwidth. With the rapid development of the Internet of Things and artificial intelligence, the amount of data that integrated circuits need to process has increased significantly, and the existing on-chip signal transmission method can no longer meet the needs of communication. The transmission speed of photons in waveguides is much faster than that of electrons in conductors and semiconductors, and the optical signals in the transmission process will not interfere with each other, and there is no limitation of metal wire capacitance and inductance. Therefore, silicon-based photonic integrated circuits compatible with traditional silicon integration processes have been proposed.

[0003] The choice of wavelength for optical communication mainly depends on the transmission loss of light in the optical waveguide. The wavelength range of 1260nm to 1625nm is called the low-loss wavelength region, among which the C-band (1530nm to 1565nm) has the lowest loss and the widest range of use. The representative wavelength of the C-band is 1550nm, but silicon is almost transparent to the light in this communication band. Therefore, silicon-based germanium or indium gallium arsenic (InGaAs) detectors are selected to detect infrared light. Of the two, germanium materials have low cost, high thermal conductivity, and are compatible with silicon processes, so they are more widely used.

[0004] Like amplitude, phase and frequency, polarization is one of the basic properties of light and can be used to record, process and store information. The polarization of light refers to the selective vibration of the direction of the electric field vector in the light wave. Light polarization has many applications in life, including liquid crystal displays that use polarizers to control the arrangement of liquid crystal molecules, polarized sunglasses and 3D displays. As one of the basic properties of light, the polarization property of light can also carry and store more information. For example, in fiber optic communications, polarization multiplexing technology can use light waves with different polarization states to transmit signals in the same optical fiber, thereby increasing the transmission capacity of the optical fiber. Polarization contains information about the imaging environment, such as the properties of materials and tissues, surface roughness, the shape and texture of reflective surfaces, the orientation of light emitters, or the optical activity of various materials, which is usually not reflected in color, intensity and spectral content.

[0005] At present, polarization-dependent optical systems contain bulky and costly optical components, which are not conducive to optoelectronic integration. The on-chip polarization detectors have complex structures and complicated preparation processes. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the present invention provides a high-speed self-starting silicon light polarization detection device using a single photodetector. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0007] A first aspect of an embodiment of the present invention provides a high-speed self-starting silicon optical polarization detection device using a single photodetector, comprising: a two-dimensional grating coupler, an optical waveguide, and a self-starting silicon-based germanium photodetector with a symmetrical energy band structure;

[0008] The two-dimensional grating coupler is connected to the optical waveguide, and the optical waveguide is connected to two PN junctions of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure;

[0009] Among them, the two-dimensional grating coupler receives vertical incident light and decomposes the polarization state of the incident light into two orthogonal polarization states. The two orthogonal polarization states of light are respectively transmitted to the two PN junctions of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure through the optical waveguide coupling, so as to realize the self-starting silicon-based germanium photodetector with a symmetrical energy band structure to generate positive response and negative response.

[0010] In one embodiment of the present invention, the two-dimensional grating coupler comprises: a rectangular coupling portion, a first coupling arm and a second coupling arm;

[0011] The rectangular coupling portion is provided with a plurality of circular grooves, and the plurality of circular grooves form an array;

[0012] The first coupling arm and the second coupling arm are respectively arranged on two adjacent sides of the rectangular coupling portion;

[0013] The first coupling arm and the second coupling arm are both connected to one end of the optical waveguide.

[0014] In one embodiment of the present invention, the optical waveguide comprises: a first sub-optical waveguide and a second sub-optical waveguide;

[0015] The first coupling arm is connected to one end of the first sub-optical waveguide, and the other end of the first sub-optical waveguide is connected to a PN junction of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure;

[0016] The second coupling arm is connected to one end of the second sub-optical waveguide, and the other end of the second sub-optical waveguide is connected to another PN junction of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure.

[0017] In one embodiment of the present invention, one end of the doped silicon layer of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure is grounded.

[0018] In one embodiment of the present invention, the two-dimensional grating coupler receives vertical incident light, decomposes the polarization state of the incident light into an Ex polarization component and an Ey polarization component, and couples the Ex polarization component and the Ey polarization component into the first sub-optical waveguide and the second sub-optical waveguide in TE mode, respectively.

[0019] In one embodiment of the present invention, the doped silicon layer of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure is a PNP type or NPN type structure.

[0020] In one embodiment of the present invention, it is prepared using a silicon photonic platform.

[0021] In one embodiment of the present invention, the operating bandwidth is greater than or equal to 50 GHz.

[0022] In one embodiment of the present invention, the incident light is infrared light;

[0023] The two orthogonal polarization states of light are respectively transmitted to the two PN junctions of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure through the optical waveguide coupling, so as to realize the self-starting silicon-based germanium photodetector with a symmetrical energy band structure to generate positive response and negative response, including:

[0024] After the two orthogonal polarization states of light are respectively coupled and transmitted to the two PN junctions of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure through the optical waveguide, the infrared light penetrates the doped silicon layer and is absorbed by the germanium, and the photogenerated carriers generated in the germanium diffuse into the doped silicon layer. The photogenerated carriers are directionally separated in the spatial electric field of the PN junction, and opposite photocurrents are generated at the positions of the two PN junctions, so as to realize the positive response and negative response of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure.

[0025] Beneficial effects of the present invention:

[0026] The present invention has a simple structure and is easier to integrate with the existing silicon process platform for preparation. The present invention can complete the detection of the polarization information of the incident light using only one photodetector structure, and all the polarization information is contained in the output of an electrical signal, which greatly improves the utilization rate of the device structure and the information density contained in the output signal, reduces the system complexity, improves the integration, reduces the chip area, and reduces the cost. In addition, high-speed devices working under zero power consumption conditions are more suitable for Internet of Things applications with miniaturization, low power consumption and low cost requirements.

[0027] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 A schematic diagram of the structure of a light polarization state detection chip based on a waveguide grating coupler provided by prior art three;

[0031] Figure 2 A schematic diagram of the structure of a polarization analysis device based on thin-film lithium niobate provided by prior art 4;

[0032] Figure 3 A schematic diagram of the structure of a high-speed self-starting silicon light polarization detection device using a single photodetector provided in an embodiment of the present invention;

[0033] Figure 4 A schematic diagram of the structure of a two-dimensional grating coupler provided in an embodiment of the present invention;

[0034] Figure 5 Schematic diagram of a PNP silicon structure and an NPN silicon structure of a self-starting silicon-based germanium photodetector with a symmetrical energy band structure provided by an embodiment of the present invention;

[0035] Figure 6 The energy band diagram of the PNP silicon structure provided by the embodiment of the present invention when the band is flat. DETAILED DESCRIPTION

[0036] In the related technology, there are five types of on-chip polarization detectors:

[0037] 1. Metasurface: A metasurface is prepared on the detector surface as a polarization recognition layer, and then integrated into an additional photodetection layer for signal readout. Metamaterial is a material composed of artificially designed subwavelength structural units, which has properties and light field control capabilities that natural materials do not have. The metasurface is a two-dimensional periodic array composed of subwavelength structural units, and its thickness is usually much smaller than the wavelength. Metasurface light field control mechanism Metasurfaces have a high degree of freedom in design and can flexibly control the interaction process between the structure and the light field, thereby finely controlling the phase and amplitude of the incident light in each polarization state. With the help of phase control, the metasurface can control the reflection or refraction of light, thereby splitting the incident light according to the polarization state. With the help of amplitude control, the metasurface can achieve efficient absorption of specific polarized light, thereby improving the efficiency of light energy utilization. This structure mainly uses the different transmittance or reflectivity of the polarization recognition layer in different polarization directions to change the excitation intensity of the detector, thereby generating photocurrents of different sizes.

[0038] 2. Anisotropic materials: Many materials have intrinsic anisotropic structures, which leads to different absorption coefficients for linearly polarized light in different polarization directions, and produces different photocurrent signals. For example, two-dimensional materials and perovskite materials such as black phosphorus, germanium arsenide, and rubidium sulfide, materials with in-plane anisotropy have shown high responsiveness and dichroic ratio in the field of linear polarization detection, and their detection range covers various bands from ultraviolet to near infrared.

[0039] 3. A light polarization state detection chip based on waveguide grating coupler, such as Figure 1 As shown. It includes a waveguide grating coupler with a grating region and four output ports. The four output ports of the waveguide grating coupler are divided into two groups perpendicular to each other. The two groups of output ports are respectively connected to the same multimode interference coupler through a first single-mode waveguide, and are respectively connected to two first photodetectors through a second single-mode waveguide; the first single-mode waveguide, the second single-mode waveguide and the output port of the waveguide grating coupler are all connected through a mode converter; the multimode interference coupler is connected to the two second photodetectors through two third single-mode waveguides. The device involved is based on an optical waveguide device, can be integrated on the same substrate, has a high degree of integration, and can be used in the field of optical communication and on-chip / inter-chip optical interconnection.

[0040] 4. Polarization analysis device and method based on thin film lithium niobate, such as Figure 2As shown. The device includes a lithium niobate film, an optical coupler, a directional coupler, a multimode interference coupler, a grating coupler, a photodetector, a polarization analysis component and a lithium niobate optical waveguide. The optical coupler, the directional coupler, the multimode interference coupler, the grating coupler, the photodetector, the polarization analysis component and the lithium niobate optical waveguide are arranged on the lithium niobate film; the optical coupler is respectively connected to the directional coupler and the multimode interference coupler through the lithium niobate optical waveguide, the directional coupler, the multimode interference coupler, the grating coupler, the photodetector and the polarization analysis component are connected in sequence, and the directional coupler is also connected to the grating coupler. The present invention can realize the integration of polarization analysis devices with other devices, realize feedback control, realize the miniaturization of devices, and reduce the overall delay and complexity of the system.

[0041] For the existing technology 1, it is necessary to design additional nanostructures, and the complexity of the manufacturing process and the high-precision requirements make it difficult to process. The fine structure design of the metasurface usually requires high-resolution nanomanufacturing technology, which not only makes the production process complicated, but also makes it difficult to reduce costs during mass production. In addition, device stability is also an issue that cannot be ignored. Metasurface devices are sensitive to changes in the external environment. Changes in parameters such as temperature, humidity, and mechanical stress can affect their detection performance and stability. In addition, after passing through the metasurface, multiple specific polarization states of light require multiple detectors to be converted into photocurrents, and more devices are required.

[0042] For the second existing technology, polarization detection devices made of anisotropic materials represented by two-dimensional materials and perovskites, the new materials used are difficult to integrate with silicon-based CMOS processes in the short term. Building a process line that meets the manufacturing requirements of special materials and devices will greatly increase the manufacturing cost of the device and limit its application.

[0043] The detector implementation schemes in the prior art three and four have a common disadvantage: multiple photodetectors are required. Figure 1 In the embodiment, the corresponding photoelectric detectors are 17 and 18, a total of 4 photoelectric detectors; the corresponding structure in the prior art 4 Figure 2 In the example, the corresponding photodetector is a plurality of 6. Using multiple photodetectors will increase the complexity of the detector design, and will also cause the complexity of the subsequent electrical signal processing circuit and increase the system delay. It will also increase the chip area occupied by the system and increase the chip cost.

[0044] In addition to the common shortcomings, the two-dimensional grating coupler used in the prior art three has four coupling arms, occupies a large chip area, and has a high manufacturing cost. In the preparation process of the prior art five, the thin film lithium niobate is its core part, and its manufacturing process is incompatible with the traditional silicon process. It is necessary to build a new process line compatible with the lithium niobate thin film, which is difficult to implement and has a high cost.

[0045] In order to solve the above technical problems, the present invention is further described in detail below in conjunction with specific embodiments, but the implementation methods of the present invention are not limited thereto.

[0046] like Figure 3 As shown, a first aspect of an embodiment of the present invention provides a high-speed self-starting silicon optical polarization detection device using a single photodetector, including: a two-dimensional grating coupler, an optical waveguide, and a self-starting silicon-based germanium photodetector with a symmetrical energy band structure.

[0047] The two-dimensional grating coupler is connected to an optical waveguide, and the optical waveguide is connected to two PN junctions of a self-starting silicon-based germanium photodetector with a symmetrical energy band structure.

[0048] Among them, the two-dimensional grating coupler receives vertical incident light and decomposes the polarization state of the incident light into two orthogonal polarization states. The two orthogonal polarization states of light are respectively transmitted to the two PN junctions of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure through optical waveguide coupling, so as to realize the self-starting silicon-based germanium photodetector with a symmetrical energy band structure to produce positive response and negative response.

[0049] In this embodiment, the two-dimensional grating coupler can decompose the polarization state of light vertically coupled into the chip into two orthogonal polarization states, which are coupled to the optical waveguide respectively. The light of the two polarization states is transmitted to the two junction positions of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure through the optical waveguide, and positive and negative light responses are generated respectively. Therefore, the polarization direction of the input light can be obtained from the positive and negative of the single output of the device. One end of the doped silicon layer of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure is grounded, and the bidirectional light response photodetector works in a self-starting state, does not require an additional bias voltage, and has the characteristic of zero power consumption. At the same time, by reasonably adjusting the width of the region between the P region and the N region of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure, the bandwidth of the device can reach more than 50GHz.

[0050] Furthermore, if Figure 4 As shown, the two-dimensional grating coupler includes: a rectangular coupling portion, a first coupling arm and a second coupling arm.

[0051] A plurality of circular grooves are provided on the rectangular coupling part, and the plurality of circular grooves form an array; the first coupling arm and the second coupling arm are respectively arranged on two adjacent sides of the rectangular coupling part; the first coupling arm and the second coupling arm are both connected to one end of the optical waveguide.

[0052] Further, the optical waveguide comprises: a first sub-optical waveguide and a second sub-optical waveguide;

[0053] The first coupling arm is connected to one end of the first sub-optical waveguide, and the other end of the first sub-optical waveguide is connected to a PN junction of a self-starting silicon-based germanium photodetector with a symmetrical energy band structure.

[0054] The second coupling arm is connected to one end of the second sub-optical waveguide, and the other end of the second sub-optical waveguide is connected to another PN junction of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure.

[0055] In this embodiment, because the effective refractive index of the waveguide is very different for the TE and TM modes, at the operating wavelength of 1550nm, the coupling efficiency of the TE mode is 17 times that of the TM mode, and basically no TM mode light is coupled into the optical waveguide. Therefore, one-dimensional grating couplers are almost all polarization-dependent and can only couple specific polarization states, and will produce large polarization-dependent loss (PDL) for other polarization states. The two-dimensional grating coupler can be simply understood as the effect that can be produced by two orthogonally oriented one-dimensional grating couplers, and the structure is as follows: Figure 4 As shown. The light vector propagating in a single-mode optical fiber can be decomposed into two mutually orthogonal polarization modes Ex and Ey. For the optical waveguide in the ±x direction, the two-dimensional grating coupler couples the Ex polarization component of the electromagnetic wave in free space in the TE mode; similarly, for the optical waveguide in the ±y direction, the two-dimensional grating coupler also couples the Ey polarization component of the electromagnetic wave in the TE mode, while the TM mode light is attenuated. Therefore, the two-dimensional grating coupler can decompose different polarization states in the optical fiber into two orthogonal polarization states.

[0056] The doped silicon layer of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure is a PNP or NPN structure. The polarized light split by the two-dimensional grating coupler is coupled to the self-starting silicon-based germanium photodetector structure with a symmetrical energy band structure of the PNP or NPN silicon structure through an optical waveguide. The two structures of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure are as follows Figure 5 As shown, (a) is a PNP silicon structure, and (b) is an NPN silicon structure. Two polarized lights in orthogonal directions are coupled to the positions of PN junction 1 and PN junction 2, respectively. C-band infrared light penetrates the silicon material and is absorbed by germanium. The photogenerated carriers generated in germanium enter the silicon through diffusion and are directionally separated in the spatial electric field of the silicon PN junction. For the polarized light coupled to the optical waveguide on the left side of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure, the photogenerated carriers generated after being absorbed by germanium will diffuse to the space charge region of PN junction 1 on the left; for the polarized light coupled to the optical waveguide on the right side of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure, the photogenerated carriers generated after being absorbed by germanium will diffuse to the space charge region of PN junction 2 on the right. The energy band diagram for the PNP silicon structure when it is flat band is shown as follows Figure 6As shown, (a) shows the separation of carriers by PN junction 1 on the left, and (b) shows the separation of carriers by PN junction 2 on the right. The direction of the separation of carriers by the space charge region of PN junction 1 on the left is that holes go to the left and electrons go to the right, and the direction of the generated photocurrent is to the left. The direction of the separation of carriers by the space charge region of PN junction 2 on the right is that electrons go to the left and holes go to the right, and the direction of the generated photocurrent is to the right. The self-starting silicon-based germanium photodetector with a symmetrical energy band structure of the NPN silicon structure will also produce a similar process, generating opposite photocurrents for the light received by the two junctions. In summary, the self-starting silicon-based germanium photodetector with a symmetrical energy band structure can generate positive and negative responses respectively. The direction of the photocurrent generated by the device reflects the PN junction corresponding to the received light. The greater the received light power, the greater the response generated. The magnitude of the positive response photocurrent and the negative response photocurrent can reflect the polarization information of the incident light, which also reflects the light intensity in the two coupling arms, and ultimately reflects the polarization state of the incident light.

[0057] The self-starting silicon-based germanium photodetector with a symmetrical energy band structure works under the self-starting condition of zero bias. During use, one end of the doped silicon layer is grounded and the other end reads the photocurrent. No external power input is required during the operation of the device, and the energy to generate the output photocurrent comes entirely from the incident light signal.

[0058] The carrier transit time is the time required for photogenerated carriers to pass through the depletion region of the PNP (or NPN) silicon structure under the action of an electric field and be collected by the electrode. It is determined by the drift velocity of electrons and holes under the electric field and the width of the depletion region. By rationally designing the doping concentration of the P and N regions in silicon and the width of the middle region between the P and N regions, widening the depletion region, and increasing the electric field in the depletion region, the drift velocity of carriers can be increased, the operating bandwidth of the device can be widened, and a bandwidth of more than 50GHz can be achieved.

[0059] In this embodiment, a high-speed self-starting silicon optical polarization detection device using a single photodetector can work in the C band and be integrated with the silicon optical platform. At the same time, the detector has zero power consumption and large bandwidth. Only one photodetector structure can be used to detect the polarization information of the incident light, and all the polarization information is contained in the output of an electrical signal.

[0060] The preparation of the high-speed self-starting silicon light polarization detection device using a single photodetector in this embodiment can be carried out using the following process flow:

[0061] First, a silicon-on-insulator (SOI) substrate is selected, and a rectangular coupling part structure is etched on the silicon layer by deep ultraviolet lithography or electron beam lithography technology to decompose the polarization state of the incident light. Then, a coupling arm and an optical waveguide structure are formed on the silicon substrate on two adjacent sides of the rectangular coupling part by photolithography and dry etching. Then, doping is performed on the silicon substrate at the output end of the optical waveguide, and then a germanium layer is selectively epitaxially grown. Then, the silicon layer and the germanium layer are etched, and electrodes are deposited, and the electrodes are connected to an external electrical signal processing circuit or chip.

[0062] The high-speed self-starting silicon light polarization detection device using a single photodetector of the present invention is more stable in the working scene than the polarization light detector based on the metasurface, and does not require the design of additional micro-nano structures, and the process is simpler. At the same time, compared with detectors based on two-dimensional materials and perovskite materials, the preparation of the present invention is easier to achieve integration with the existing silicon process platform. Compared with the traditional direct use of coupler splitting and detection, which requires multiple electrical detectors, the present invention only uses one photodetector structure to complete the detection of the polarization information of the incident light, and all the polarization information is included in the output of an electrical signal, which greatly improves the utilization rate of the device structure and the information density contained in the output signal, reduces the complexity of the system, improves the integration, reduces the chip area, and reduces the cost. In addition, high-speed devices working under zero power consumption conditions are more suitable for Internet of Things applications with miniaturization, low power consumption and low cost requirements.

[0063] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0064] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0065] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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 a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0067] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0068] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A high-speed self-starting silicon light polarization detection device using a single photodetector, characterized in that: include: Two-dimensional grating couplers, optical waveguides, and self-starting silicon-germanium photodetectors with symmetrical band structures; The two-dimensional grating coupler is connected to the optical waveguide, and the optical waveguide is connected to two PN junctions of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure; Among them, the two-dimensional grating coupler receives vertical incident light and decomposes the polarization state of the incident light into two orthogonal polarization states. The two orthogonal polarization states of light are respectively transmitted to the two PN junctions of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure through the optical waveguide coupling, so as to realize the self-starting silicon-based germanium photodetector with a symmetrical energy band structure to generate positive response and negative response.

2. A high-speed self-starting silicon light polarization detection device using a single photodetector as claimed in claim 1, characterized in that: The two-dimensional grating coupler comprises: a rectangular coupling portion, a first coupling arm and a second coupling arm; The rectangular coupling portion is provided with a plurality of circular grooves, and the plurality of circular grooves form an array; The first coupling arm and the second coupling arm are respectively arranged on two adjacent sides of the rectangular coupling portion; The first coupling arm and the second coupling arm are both connected to one end of the optical waveguide.

3. A high-speed self-starting silicon light polarization detection device using a single photodetector as claimed in claim 1, characterized in that: The optical waveguide comprises: a first sub-optical waveguide and a second sub-optical waveguide; The first coupling arm is connected to one end of the first sub-optical waveguide, and the other end of the first sub-optical waveguide is connected to a PN junction of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure; The second coupling arm is connected to one end of the second sub-optical waveguide, and the other end of the second sub-optical waveguide is connected to another PN junction of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure.

4. A high-speed self-starting silicon light polarization detection device using a single photodetector as claimed in claim 1, characterized in that: One end of the doped silicon layer of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure is grounded.

5. A high-speed self-starting silicon light polarization detection device using a single photodetector as claimed in claim 3, characterized in that: The two-dimensional grating coupler receives vertical incident light, decomposes the polarization state of the incident light into an Ex polarization component and an Ey polarization component, and couples the Ex polarization component and the Ey polarization component into the first sub-optical waveguide and the second sub-optical waveguide respectively in TE mode.

6. A high-speed self-starting silicon light polarization detection device using a single photodetector as claimed in claim 4, characterized in that: The doped silicon layer of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure is a PNP type or NPN type structure.

7. A high-speed self-starting silicon light polarization detection device using a single photodetector as claimed in claim 1, characterized in that: It was prepared using a silicon photonic platform.

8. A high-speed self-starting silicon light polarization detection device using a single photodetector as claimed in claim 1, characterized in that: The operating bandwidth is greater than or equal to 50 GHz.

9. A high-speed self-starting silicon light polarization detection device using a single photodetector as claimed in claim 1, characterized in that: The incident light is infrared light; The two orthogonal polarization states of light are respectively transmitted to the two PN junctions of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure through the optical waveguide coupling, so as to realize the self-starting silicon-based germanium photodetector with a symmetrical energy band structure to generate positive response and negative response, including: After the two orthogonal polarization states of light are respectively coupled and transmitted to the two PN junctions of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure through the optical waveguide, the infrared light penetrates the doped silicon layer and is absorbed by the germanium, and the photogenerated carriers generated in the germanium diffuse into the doped silicon layer. The photogenerated carriers are directionally separated in the spatial electric field of the PN junction, and opposite photocurrents are generated at the positions of the two PN junctions, so as to realize the positive response and negative response of the self-starting silicon-based germanium photodetector with a symmetrical energy band structure.

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