A light detector and a method for preparing the same

Abstract

The present application discloses a photodetector and a method for manufacturing the same. The photodetector includes: a first transmission waveguide, a second transmission waveguide, a first coupler, a second coupler, a wavelength converter, and a light detection structure. The first coupler is disposed between the first transmission waveguide and the wavelength converter, and the first coupler can enable optical communication between the first transmission waveguide and the wavelength converter. The wavelength converter is used to convert the wavelength of an optical signal output by the first coupler. The second coupler is disposed between the second transmission waveguide and the wavelength converter, and the second coupler can enable optical communication between the second transmission waveguide and the wavelength converter. The light detection structure is used to detect the optical signal output by the second coupler. The photodetector prepared in the present application converts light in a transparent band for silicon material into light in an opaque band, and then detects the light, thereby improving detection accuracy, avoiding the need to integrate other materials to prepare the detector, reducing the difficulty of the preparation process, and lowering production costs.

Description

Technical Field

[0001] The present application relates to the technical field of preparation and application of optical detectors, and in particular to an optical detector and a preparation method thereof. Background Art

[0002] With the progress of the times, the huge application potential of integrated optics in optical interconnection, optical computing, etc. has attracted widespread attention. Silicon photonics technology based on SOI materials has become very mature in device design and device preparation, and can be prepared on a large scale relying on CMOS process technology.

[0003] However, silicon also has its own limitations: 1. Silicon is a centrosymmetric crystal material, lacking second-order nonlinear optical effects and linear electro-optical effects, thus facing a natural disadvantage in the preparation of second-order nonlinear devices and electro-optic modulators. 2. Silicon's intrinsic absorption edge is around 1100nm. The 1310nm and 1550nm bands commonly used in integrated optics are transparent to silicon, so other materials, such as Ge, must be integrated on silicon for light detection, which greatly increases the technical difficulty.

[0004] Therefore, there is an urgent need for a technical solution for optical detectors to solve the problems of traditional detectors, such as the difficulty in preparation technology, long detection time, and the need to integrate multiple materials to increase the difficulty of integration. Summary of the Invention

[0005] In order to solve the problems of the prior art, the present invention provides a technical solution for a light detector and a method for manufacturing the same, and the technical solution is as follows:

[0006] In one aspect, a photodetector is provided, comprising: a first transmission waveguide, a second transmission waveguide, a first coupler, a second coupler, a wavelength converter, and a photodetection structure;

[0007] The first coupler is disposed between the first transmission waveguide and the wavelength converter, and is used to connect the first transmission waveguide and the wavelength converter to light conduction;

[0008] The wavelength converter is used to perform wavelength conversion on the optical signal output by the first coupler;

[0009] The second coupler is provided between the second transmission waveguide and the wavelength converter, and the second coupler can enable the second transmission waveguide to be optically connected to the wavelength converter;

[0010] The optical detection structure is used to detect the optical signal output by the second coupler.

[0011] Furthermore, the first transmission waveguide and the second transmission waveguide are spaced apart, and the wavelength converter is disposed in the space between the first transmission waveguide and the second transmission waveguide.

[0012] Furthermore, the photodetector further includes a substrate and a light isolation layer disposed on the substrate;

[0013] A light conversion layer is provided on a side of the light isolation layer away from the substrate, and the wavelength converter is provided in the light conversion layer;

[0014] The first transmission waveguide and the second transmission waveguide are disposed on a side of the light conversion layer away from the light isolation layer.

[0015] Furthermore, the photodetector further includes a conductive structure, which is arranged on a side of the second transmission waveguide away from the light conversion layer, and is used to transmit an electrical signal corresponding to the optical signal output by the second coupler output by the photodetection structure.

[0016] Furthermore, the first transmission waveguide and / or the second transmission waveguide is a ridge waveguide structure or a strip waveguide structure.

[0017] Furthermore, the wavelength converter includes at least one forward polarization structure and at least one reverse polarization structure, and the at least one forward polarization structure and the at least one reverse polarization structure are alternately arranged adjacent to each other; and / or

[0018] The wavelength converter includes a microdisk resonant structure or a microring resonant structure, and the diameter of the microdisk resonant structure or the microring resonant structure is a preset value.

[0019] Furthermore, the wavelength corresponding to the optical signal output by the first coupler is 1100nm-2000nm; the wavelength corresponding to the optical signal output by the second coupler is 600nm-1000nm.

[0020] Furthermore, the wavelength converter is made of lithium niobate.

[0021] Furthermore, the light detection structure is a metal-semiconductor-metal detection structure or a semiconductor-intrinsic region-semiconductor detection structure.

[0022] In another aspect, a method for preparing a light detector is provided, comprising the following steps:

[0023] providing a substrate;

[0024] preparing a thin film on the substrate to form a light isolation layer with a preset depth on the substrate;

[0025] Preparing a thin film based on a first preset material on a side of the light isolation layer away from the substrate to form a thin film layer with a preset depth;

[0026] Preparing a thin film based on a second preset material on a side of the thin film layer away from the light isolation layer to form a light propagation layer of a preset depth;

[0027] Etching the light propagation layer to form a first transmission waveguide and a second transmission waveguide; etching the first transmission waveguide and the second transmission waveguide to form a first coupler at a preset position of the first transmission waveguide, and forming a second coupler and a light detection structure at a preset position of the second transmission waveguide;

[0028] The thin film layer is etched to form a light conversion layer with a wavelength converter to obtain a light detector.

[0029] The present application provides a light detector and a method for manufacturing the same, which have the following technical effects:

[0030] 1. The photodetector prepared in this application can convert light in the transparent band for silicon material into light in the opaque band, and then detect the light in the opaque band, thereby improving the detection accuracy, avoiding the integration of other materials to prepare the detector, and reducing the difficulty of the preparation process.

[0031] 2. The photodetector prepared in this application utilizes the second-order nonlinear characteristics of lithium niobate material. By etching the lithium niobate material, a wavelength converter of lithium niobate material is generated. The wavelength converter has a frequency doubling effect and can convert the wavelength of near-infrared light into the wavelength range of visible light, which can then be detected by a photodetection structure made of silicon material. At the same time, this structure can realize the hybrid integration of silicon photonics and lithium niobate electro-optical modulators, thereby using two materials to simultaneously realize the full integration of silicon photonic passive devices and main components of electro-optical modulators, which has broad application prospects.

[0032] 3. The wavelength converter in this application significantly improves the efficiency of nonlinear conversion during nonlinear optical conversion, shortens the detection time of the light detector, and has good applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0034] Figure 1 A schematic diagram of the structure of a light detector provided in an embodiment of the present application;

[0035] Figure 2 A schematic diagram of the structure of a photodetector with a micro-ring resonant structure as the wavelength converter provided in an embodiment of the present application;

[0036] Figure 3 A schematic structural diagram of a photodetector having a wavelength converter micro-disk resonant structure provided in an embodiment of the present application;

[0037] Figure 4 A schematic diagram of the structure of a photodetector with a straight waveguide structure as the wavelength converter provided in an embodiment of the present application;

[0038] Figure 5 A cross-sectional view of a light detector provided in an embodiment of the present application;

[0039] Figure 6 A schematic diagram of a semiconductor-intrinsic region-semiconductor detection structure provided in an embodiment of the present application;

[0040] Figure 7 A schematic flow chart of a method for preparing a light detector provided in an embodiment of the present application;

[0041] Among them, the figure is marked as follows: 1-first coupler; 2-wavelength converter; 3-second coupler; 4-light detection structure; 5-forward polarization structure; 6-reverse polarization structure; 7-substrate; 8-light isolation layer; 9-light conversion layer; 101-first transmission waveguide; 102-second transmission waveguide; 11-conductive structure; 12-microring resonant structure; 13-microdisk resonant structure. DETAILED DESCRIPTION

[0042] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0043] It should be noted that, in the description of the invention of this application, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. "One embodiment" or "embodiment" referred to herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention.

[0044] The present invention provides a light detector. Figure 1 , which is a structural schematic diagram of a light detector provided in an embodiment of the present application, comprising: a first transmission waveguide (101), a second transmission waveguide (102), a first coupler (1), a second coupler (3), a wavelength converter (2) and a light detection structure (4); the first coupler (1) is arranged between the first transmission waveguide (101) and the wavelength converter (2), wherein the first coupler (1) is used to conduct light between the first transmission waveguide (101) and the wavelength converter (2); the wavelength converter (2) is used to perform wavelength conversion on the light signal output by the first coupler (1); the second coupler (3) is arranged between the second transmission waveguide (102) and the wavelength converter (2), wherein the second coupler (3) can conduct light between the second transmission waveguide (102) and the wavelength converter (2); and the light detection structure (4) is used to detect the light signal output by the second coupler (3).

[0045] In the embodiment of the present application, the first coupler (1) and the second coupler (3) are both devices obtained by etching a light transmission layer of a preset material. The first coupler (1) and the second coupler (3) can conduct light between the transmission waveguide and the wavelength converter (2), so that optical signals can be transmitted between the transmission waveguide and the wavelength converter (2).

[0046] In one embodiment, the first coupler (1) and the second coupler (3) are both devices obtained by etching silicon material, and the first coupler (1) and the second coupler (3) are both wedge-shaped couplers. The first coupler (1) is located on a side of the first transmission waveguide (101) close to the wavelength converter (2) and is used for optical communication between the first transmission waveguide (101) and the wavelength converter (2). The second coupler (3) is located on a side of the second transmission waveguide (102) close to the wavelength converter (2) and is used for optical communication between the second transmission waveguide (102) and the wavelength converter (2).

[0047] It should be noted that the material of the first coupler (1) and the second coupler (3) described in the present application is not limited to the above-mentioned silicon material, and can also be other materials that can achieve light conduction, for example, this application does not make specific limitations here.

[0048] In the embodiment of the present application, the first transmission waveguide (101) and the second transmission waveguide (102) are both transmission waveguides obtained by etching a light transmission layer of a preset material. For example, the preset material is a silicon material, and the first transmission waveguide (101) and the second transmission waveguide (102) are both silicon transmission waveguides obtained by etching the silicon material. It should be noted that the present application is not limited to generating the first transmission waveguide (101) and the second transmission waveguide (102) by etching the above-mentioned silicon material, and the first transmission waveguide (101) and the second transmission waveguide (102) may be formed by etching other materials, and no specific limitation is made here.

[0049] In an optional embodiment, the material of the wavelength converter (2) includes lithium niobate.

[0050] In the embodiment of the present application, the wavelength converter (2) is a device obtained by etching a thin film layer of a predetermined material, and the wavelength converter (2) is capable of converting the wavelength of light to obtain an optical signal that can be detected by the light detection structure (4). For example, the wavelength of near-infrared light is converted into a wavelength range of visible light.

[0051] In an optional embodiment, the wavelength corresponding to the optical signal output by the first coupler (1) is 1100nm-2000nm; the wavelength corresponding to the optical signal output by the second coupler (3) is 600nm-1000nm.

[0052] In one embodiment, the wavelength converter (2) is a wavelength converter (2) obtained by etching lithium niobate material. The wavelength converter (2) has the characteristics of lithium niobate material, that is, it has a good second-order nonlinear photoelectric effect and can produce a frequency doubling effect. The wavelength converter (2) can convert the wavelength of the optical signal with a wavelength of 1100nm-2000nm output by the first coupler (1) so that the converted wavelength can be within 600nm-1000nm. The wavelength converter (2) is coupled to the light detection structure (4) through the second coupler (3) so that the converted optical signal can be detected by the light detection structure (4) and then detected. For example, the near-infrared light in the 1310nm-1550nm band is converted into light in the 655nm-755nm band. The light in the 655nm-755nm band is within the wavelength range that can be detected by the light detection structure (4), and the light in the 655nm-755nm band is detected.

[0053] It should be noted that the wavelength converter (2) described in the present application is not limited to the above-mentioned light wavelength conversion range, and can also convert the wavelength of ultraviolet light into the wavelength range of visible light, or other forms of light wavelength conversion. In addition, the material of the wavelength converter of the present application is not limited to the above-mentioned lithium niobate material, and can also be other materials that can achieve light wavelength conversion. For example, this application does not make specific restrictions here.

[0054] In the embodiment of the present application, the wavelength of light is converted into the wavelength range of visible light, so that the light detection structure (4) can detect according to the detected light signal, thereby improving the detection accuracy, reducing the difficulty of the preparation process, facilitating operation, and avoiding the integration of other materials to prepare detectors, thereby reducing production costs; at the same time, the above structure can also realize the hybrid integration of silicon photonics and lithium niobate electro-optical modulators, thereby using two materials to simultaneously realize the full integration of silicon photonics passive devices and electro-optical modulator main components, which has broad application prospects.

[0055] In an optional embodiment, the first transmission waveguide (101) and the second transmission waveguide (102) are spaced apart, wherein the wavelength converter (2) is arranged in the space between the first transmission waveguide (101) and the second transmission waveguide (102). In a specific embodiment, see Figure 1 The length of the interval setting is not limited to Figure 1 The length shown can also be set at intervals of other lengths, and this application does not make any specific limitations here.

[0056] In an optional embodiment, the photodetector further comprises a substrate (7) and a light isolation layer (8) arranged on the substrate; a light conversion layer (9) is provided on a side of the light isolation layer (8) away from the substrate (7), and the wavelength converter (2) is arranged in the light conversion layer (9); and a first transmission waveguide (101) and a second transmission waveguide (102) are arranged on a side of the light conversion layer (9) away from the light isolation layer (8).

[0057] In the embodiments of this application, Figure 5 As shown, it is a cross-sectional view of a light detector provided by an embodiment of the present application, wherein the light isolation layer (8) is used to isolate the light transmitted by the first transmission waveguide (101), and the material of the light conversion layer (9) is lithium niobate. It should be noted that the material of the light conversion layer (9) is not limited to the above-mentioned lithium niobate material, and can also be other materials that can achieve light conversion, as long as the other materials have a good second-order nonlinear photoelectric effect and can produce a frequency doubling effect. For example, this application does not make specific restrictions here.

[0058] In an optional embodiment, the wavelength converter (2) comprises at least one forward polarization structure (5) and at least one reverse polarization structure (6), and the at least one forward polarization structure (5) and the at least one reverse polarization structure (6) are alternately arranged adjacent to each other; and / or

[0059] The wavelength converter (2) comprises a micro-disk resonant structure (13) or a micro-ring resonant structure (12), wherein the diameter of the micro-disk resonant structure (13) or the micro-ring resonant structure (12) is a preset value.

[0060] In the examples of this application, see Figure 1 In the wavelength converter (2), the forward polarization structure (5) and the reverse polarization structure (6) are alternately arranged adjacent to each other, and the wavelength conversion of the light is achieved by alternating transmission of the forward polarization structure (5) and the reverse polarization structure (6). It should be noted that the number of the forward polarization structure (5) and the reverse polarization structure (6) is not limited here and can be set according to actual conditions.

[0061] In a specific embodiment, Figure 2 As shown, it is a schematic diagram of the structure of a photodetector with a micro-ring resonant structure in which the wavelength converter provided by the embodiment of the present application is a micro-ring resonant structure. Figure 3 As shown, it is a structural schematic diagram of a light detector with a wavelength converter micro-disk resonant structure provided in an embodiment of the present application. The wavelength converter (2) may also include a micro-disk resonant structure (13) or a micro-ring resonant structure (12). In specific implementation, the structure of the wavelength converter (2) may be selected according to actual conditions and is not specifically limited here.

[0062] Furthermore, the wavelength converter (2) may also include a straight waveguide structure, such as Figure 4 As shown, it is a structural schematic diagram of a light detector with a straight waveguide structure in which the wavelength converter provided in an embodiment of the present application is a wavelength converter. In a specific embodiment, the straight waveguide structure realizes wavelength conversion of the optical signal by correspondingly setting the height dimension, width dimension and length scale of the lithium niobate waveguide. For example, the height dimension of the lithium niobate waveguide is set to 100nm-800nm, the width dimension is set to 600nm-1500nm and the length scale is set to 100nm-20000um, thereby realizing the conversion of an optical signal with a wavelength of 1550nm to an optical signal with a wavelength of 775nm. It should be noted that the propagation constant of the converted optical signal with a wavelength of 775nm is the same as that of the optical signal with a wavelength of 1550nm.

[0063] It should be noted that the wavelength converter (2) is not limited to the above structure, and may also be other structures capable of achieving optical wavelength conversion, for example, which is not specifically limited in this application.

[0064] For example, the process of light detection is described below by taking near-infrared light of 1550 nm and 1310 nm wavelengths as examples through the structure of the above-mentioned light detector. For example, near-infrared light of 1550 nm wavelength is transmitted from other waveguides to the first transmission waveguide (101), and the near-infrared light of 1550 nm wavelength is transmitted along the first transmission waveguide (101) to the first coupler (1), and is coupled to the wavelength converter (2) through the first coupler (1). The wavelength converter (2) converts the near-infrared light of 1550 nm wavelength coupled out of the first coupler (1) into a light wave of 775 nm wavelength through the action of the forward polarization structure (5) and the reverse polarization structure (6). The light wave of 775 nm wavelength is coupled to the second transmission waveguide (102) through the second coupler (3), and is absorbed by the second transmission waveguide (102) at the same time, thereby generating photogenerated carriers. The light detection structure (4) generates a corresponding electrical signal according to the received photogenerated carriers, thereby determining the magnitude of the light intensity, and completing the detection of the light.

[0065] It should be noted that when performing wavelength conversion on near-infrared light with a wavelength of 1550 nm, the structure of the wavelength converter (2) can also be a micro-disk resonant structure (13), a micro-ring resonant structure (12) or a straight waveguide structure to convert the near-infrared light with a wavelength of 1550 nm coupled out by the first coupler (1) into a light wave with a wavelength of 775 nm.

[0066] For another example, near-infrared light with a wavelength of 1310 nm is transmitted from other waveguides to the first transmission waveguide (101), and the near-infrared light with a wavelength of 1310 nm is transmitted along the first transmission waveguide (101) to the first coupler (1), and is coupled to the wavelength converter (2) through the first coupler (1). The wavelength converter (2) converts the near-infrared light with a wavelength of 1310 nm coupled out of the first coupler (1) into a light wave with a wavelength of 655 nm through the action of the forward polarization structure (5) and the reverse polarization structure (6). The light wave with a wavelength of 655 nm is coupled to the second transmission waveguide (102) through the second coupler (3), and is absorbed by the second transmission waveguide (102) at the same time, thereby generating photogenerated carriers. The light detection structure (4) generates a corresponding electrical signal according to the received photogenerated carriers, thereby determining the magnitude of the light intensity and completing the detection of the light.

[0067] It should be noted that when performing wavelength conversion on near-infrared light with a wavelength of 1310 nm, the structure of the wavelength converter (2) can also be a micro-disk resonant structure (13), a micro-ring resonant structure (12) or a straight waveguide structure to convert the near-infrared light with a wavelength of 1550 nm coupled out by the first coupler (1) into a light wave with a wavelength of 775 nm.

[0068] In an optional embodiment, the photodetector further includes a conductive structure (11), which is arranged on a side of the second transmission waveguide (102) away from the light conversion layer (9), wherein the conductive structure (11) is used to transmit an electrical signal corresponding to the optical signal output by the second coupler (3) output by the light detection structure (4).

[0069] In the embodiment of the present application, the conductive structure (11) is a structure obtained by etching a predetermined material, and the conductive structure (11) can derive the electrical signal output by the light detection structure (4). For example, the conductive structure (11) is a structure obtained by etching a gold material. It should be noted that the conductive structure (11) of the present application is not limited to the aforementioned gold material, and can also be other conductive materials, which is not specifically limited here.

[0070] In an optional embodiment, the first transmission waveguide (101) and / or the second transmission waveguide (102) is a ridge waveguide structure or a strip waveguide structure. It should be noted that the structure of the first transmission waveguide (101) and / or the second transmission waveguide (102) may also be the structure of other transmission waveguides, which is not specifically limited here.

[0071] In an optional embodiment, the light detection structure (4) is a metal-semiconductor-metal detection structure or a semiconductor-intrinsic region-semiconductor detection structure.

[0072] In the embodiment of the present application, the light detection structure (4) is a device formed by etching a preset position of the second transmission waveguide (102). The light detection structure (4) can convert the optical signal into an electrical signal, thereby realizing the detection of light. Figure 1 The optical detection structure (4) is a metal-semiconductor-metal detector, i.e., an MSM detector. The structure of the metal-semiconductor-metal detector is a cross-finger metal electrode structure. At the same time, in order to match the cross-finger metal electrode structure of the silicon waveguide layer, the conductive structure (11) is also designed as a cross-finger metal electrode to form a metal-semiconductor junction with the silicon waveguide layer.

[0073] like Figure 6As shown, it is a schematic diagram of the semiconductor-intrinsic region-semiconductor detection structure provided by an embodiment of the present application, wherein the optical detection structure (4) is a semiconductor-intrinsic region-semiconductor detector, i.e., a PIN detector. The preparation process of the semiconductor-intrinsic region-semiconductor detector is to inject P-type impurities into a preset position area of ​​the silicon waveguide layer to form a P-type doped region, and to inject N-type impurities on the right side of the preset position to form an N-type doped region, and to set an intrinsic region between the P-type doped region and the N-type doped region, and to set an electrode structure on the right side of the P-type doped region and on the left side of the N-type doped region, wherein the electrode structure is in ohmic contact with the P-type doped region and the N-type doped region, and deposit electrodes to complete the preparation of the device.

[0074] It can be seen from the above technical solutions of the embodiments of the present application that the present application has the following technical effects:

[0075] The photodetector prepared in the present application utilizes the second-order nonlinear characteristics of lithium niobate material. By etching the lithium niobate material, a wavelength converter of lithium niobate material is generated. The wavelength converter has a frequency doubling effect and can convert the wavelength of near-infrared light into the wavelength range of visible light, which can then be detected by a photodetection structure made of silicon material. The preparation process of this process is simple, easy to operate and has a high yield, while also reducing production costs. At the same time, the structure can realize the hybrid integration of silicon photonics and lithium niobate electro-optical modulators, thereby using two materials to simultaneously realize the full integration of silicon photonic passive devices and main components of electro-optical modulators, which has broad application prospects. The wavelength converter in the present application significantly improves the efficiency of nonlinear conversion and shortens the detection time of the photodetector during the nonlinear optical conversion process, and has good applicability.

[0076] The present invention also provides a method for preparing a light detector. Figure 7 , which is a flow chart of a method for preparing a light detector provided in an embodiment of the present application, comprising the following steps:

[0077] S1: providing a substrate (7);

[0078] It should be noted that, in the implementation of this application, the substrate (7) can be a silicon substrate or other substrate materials, which are not defined here.

[0079] S2: preparing a thin film on a substrate (7) to form a light isolation layer (8) of a preset depth on the substrate (7);

[0080] In the embodiment of the present application, the material of the optical isolation layer (8) can be silicon dioxide, and the thickness of the optical isolation layer (8) made of silicon dioxide is 2000nm-9000nm, which is used to isolate the optical signal transmitted by the first transmission waveguide (101). The method for preparing the thin film can include one of ion implantation plus bonding transfer process, electron beam evaporation, magnetron sputtering and atomic layer deposition. The method for preparing the thin film can be determined according to the specific actual situation and is not specifically limited here.

[0081] In a specific embodiment, the thickness of the light isolation layer (8) can also be 2000nm-4000nm, 4000nm-6000nm and 6000nm-9000nm, etc. In the embodiment of the present application, the optimal thickness of the light isolation layer (8) is 4000nm-6000nm.

[0082] S3: preparing a thin film based on a first preset material on a side of the light isolation layer (8) away from the substrate (7) to form a thin film layer with a preset depth;

[0083] In the embodiment of the present application, the thin film layer is a lithium niobate thin film layer, the light conversion layer (9) is a lithium niobate waveguide layer formed by etching the lithium niobate thin film layer, and the wavelength converter is a lithium niobate wavelength converter. It should be noted that the method for preparing the thin film is as described above and will not be repeated here.

[0084] S4: preparing a thin film based on a second preset material on a side of the thin film layer away from the light isolation layer (8) to form a light propagation layer of a preset depth;

[0085] It should be noted that the method for preparing the film is as described above and will not be repeated here.

[0086] In an optional embodiment, the thickness of the light propagation layer is 300 nm-700 nm.

[0087] Furthermore, the thickness of the light propagation layer can be 300nm-400nm, 400nm-500nm, 500nm-600nm, 600nm-700nm, etc. In the application embodiment, the optimal thickness of the light propagation layer is 500nm-600nm.

[0088] S5: etching the light propagation layer to form a first transmission waveguide (101) and a second transmission waveguide (102); etching the first transmission waveguide (101) and the second transmission waveguide (102) to form a first coupler (1) at a preset position of the first transmission waveguide (101), and forming a second coupler (3) and a light detection structure (4) at a preset position of the second transmission waveguide (102);

[0089] In the embodiment of the present application, the light propagation layer is a silicon thin film layer, the first transmission waveguide (101) and the second transmission waveguide (102) are silicon waveguide layers formed by etching the silicon thin film layer, the first coupler (1) and the second coupler (3) are both manufactured by etching a preset position of the silicon waveguide layer, the first coupler (1) and the second coupler (3) are both wedge-shaped couplers, and the light detection structure (4) is manufactured by etching a preset position of the silicon waveguide layer. The specific etching method is not defined herein.

[0090] S6: Etching the thin film layer to form a light conversion layer (9) having a wavelength converter (2) to obtain a light detector.

[0091] In an optional embodiment, the thickness of the light conversion layer (9) is 2000nm-9000nm.

[0092] Furthermore, the thickness of the light conversion layer (9) can be 2000nm-4000nm, 4000nm-6000nm and 6000nm-9000nm, etc. In the application embodiment, the optimal thickness of the light conversion layer (9) is 4000nm-6000nm;

[0093] It can be seen from the above technical solutions of the embodiments of the present application that the present application has the following technical effects:

[0094] 1. The photodetector prepared in this application can convert light in the transparent band for silicon material into light in the opaque band, and then detect the light in the opaque band, thereby improving the detection accuracy, avoiding the integration of other materials to prepare the detector, and reducing the difficulty of the preparation process.

[0095] 2. The photodetector prepared in this application utilizes the second-order nonlinear characteristics of lithium niobate material. By etching the lithium niobate material, a wavelength converter of lithium niobate material is generated. The wavelength converter has a frequency doubling effect and can convert the wavelength of near-infrared light into the wavelength range of visible light, which can then be detected by a photodetection structure made of silicon material. At the same time, this structure can realize the hybrid integration of silicon photonics and lithium niobate electro-optical modulators, thereby using two materials to simultaneously realize the full integration of silicon photonic passive devices and main components of electro-optical modulators, which has broad application prospects.

[0096] 3. The wavelength converter in this application significantly improves the efficiency of nonlinear conversion during nonlinear optical conversion, shortens the detection time of the light detector, and has good applicability.

[0097] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A light detector, characterized in that: include: A first transmission waveguide (101), a second transmission waveguide (102), a first coupler (1), a second coupler (3), a wavelength converter (2), and a light detection structure (4); The first coupler (1) is arranged between the first transmission waveguide (101) and the wavelength converter (2), and the first coupler (1) is used to conduct light between the first transmission waveguide (101) and the wavelength converter (2); The wavelength converter (2) is used to perform wavelength conversion on the optical signal output by the first coupler (1); The second coupler (3) is arranged between the second transmission waveguide (102) and the wavelength converter (2), and the second coupler (3) is capable of enabling the second transmission waveguide (102) and the wavelength converter (2) to be optically connected; The light detection structure (4) is used to detect the light signal output by the second coupler (3); The wavelength converter (2) is obtained by etching a thin film layer of a preset material, wherein the preset material includes lithium niobate; the wavelength converter (2) includes a lithium niobate waveguide layer, and the thickness of the lithium niobate waveguide layer is 100nm-800nm; the wavelength converter (2) is used to convert the wavelength of the 1100nm-2000nm optical signal output by the first coupler (1) to within 600nm-1000nm, and transmit the optical signal after the wavelength conversion to the second coupler (3).

2. The optical detector according to claim 1, wherein: The first transmission waveguide (101) and the second transmission waveguide (102) are arranged at intervals, and the wavelength converter (2) is arranged in the interval between the first transmission waveguide (101) and the second transmission waveguide (102).

3. The optical detector according to claim 1, wherein: The photodetector further comprises a substrate (7) and a light isolation layer (8) arranged on the substrate; A light conversion layer (9) is provided on a side of the light isolation layer (8) away from the substrate (7), and the wavelength converter (2) is arranged in the light conversion layer (9); The first transmission waveguide (101) and the second transmission waveguide (102) are arranged on a side of the light conversion layer (9) away from the light isolation layer (8).

4. The optical detector according to claim 3, wherein: The light detector further comprises a conductive structure (11), the conductive structure (11) being arranged on a side of the second transmission waveguide (102) away from the light conversion layer (9), and the conductive structure (11) being used to transmit an electrical signal corresponding to the optical signal output by the second coupler (3) output by the light detection structure (4).

5. The light detector according to claim 1, wherein The first transmission waveguide (101) and / or the second transmission waveguide (102) is a ridge waveguide structure or a strip waveguide structure.

6. The optical detector according to claim 1, wherein: The wavelength converter (2) comprises at least one forward polarization structure (5) and at least one reverse polarization structure (6), wherein the at least one forward polarization structure (5) and the at least one reverse polarization structure (6) are alternately arranged adjacent to each other; and / or The wavelength converter (2) comprises a micro-disk resonant structure (13) or a micro-ring resonant structure (12), and the diameter of the micro-disk resonant structure (13) or the micro-ring resonant structure (12) is a preset value.

7. The optical detector according to claim 1, wherein: The wavelength of the optical signal output by the first coupler (1) corresponds to 1100nm-2000nm; the wavelength of the optical signal output by the second coupler (3) corresponds to 600nm-1000nm.

8. The optical detector according to claim 1, wherein: The light detection structure (4) is a metal-semiconductor-metal detection structure or a semiconductor-intrinsic region-semiconductor detection structure.

9. A method for preparing a photodetector according to any one of claims 1 to 8, characterized in that: The following steps are involved: providing a substrate (7); preparing a thin film on the substrate (7) to form a light isolation layer (8) of a preset depth on the substrate (7); Preparing a thin film based on a first preset material on a side of the light isolation layer (8) away from the substrate (7) to form a thin film layer with a preset depth; preparing a thin film based on a second preset material on a side of the thin film layer away from the light isolation layer (8) to form a light propagation layer of a preset depth; The light propagation layer is etched to form a first transmission waveguide (101) and a second transmission waveguide (102); the first transmission waveguide (101) and the second transmission waveguide (102) are etched to form a first coupler (1) at a preset position of the first transmission waveguide (101), and a second coupler (3) and a light detection structure (4) at a preset position of the second transmission waveguide (102); The thin film layer is etched to form a light conversion layer (9) having a wavelength converter (2), thereby obtaining the light detector.

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