All-optical solar blind ultraviolet light detector based on gallium oxide optical waveguide and preparation method of all-optical solar blind ultraviolet light detector

Abstract

The invention relates to the technical field of ultraviolet light detector preparation, in particular to an all-optical solar blind ultraviolet light detector based on a gallium oxide optical waveguide and a preparation method of the all-optical solar blind ultraviolet light detector. The detector sequentially comprises an input straight waveguide, an input conical waveguide, a multimode interference area, an output conical waveguide and an output straight waveguide in the light propagation direction. The input straight waveguide and the output straight waveguide are equal in length and width; the input conical waveguide and the output conical waveguide are equal in length and width; a substrate and a gallium oxide optical waveguide layer are arranged in the vertical direction from bottom to top; the thickness of the substrate is 0.2-1mm, and the thickness of the gallium oxide optical waveguide layer is 0.3-2mu m. The device has the advantages that optical detection is realized by utilizing the change of a self-mirror image point of multimode interference, optical signals do not need to be converted into electric signals, and a passive working function is realized; the principle of light-induced refractive index change is utilized, and drift motion of carriers is not involved, so that the signal-to-noise ratio is very high; and the structure is simple and easy to realize.

Description

Technical Field

[0001] The invention relates to the technical field of ultraviolet light detection device preparation, and in particular to an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide and a preparation method thereof. Background Art

[0002] With the continuous advancement of science and technology, photodetectors have been widely used in military and civilian fields. The day-blind ultraviolet band of sunlight is completely absorbed by the ozone layer and does not exist in the natural environment. The detection interference is extremely low, and it is more applicable in medical diagnosis, missile guidance, environmental monitoring, etc. However, the current traditional vacuum photomultiplier tubes have the disadvantages of large size and high operating voltage, while silicon-based solid photodetectors require optical filters to alleviate the response to stray light.

[0003] Gallium oxide is an ultra-wide bandgap semiconductor material. Its most stable crystal form is the monoclinic β phase, with a bandgap width of about 4.9 eV. It can be made into single crystals and thin film materials by a variety of technologies, and has good thermal and chemical stability. Its light response is in the solar-blind ultraviolet band, and it has the greatest application value in the field of solar-blind ultraviolet detection.

[0004] At present, the solar-blind ultraviolet detection of gallium oxide is based on the structure of photoconductive or photovoltaic devices, which requires the application of electric fields to transport carriers. It has problems such as low signal-to-noise ratio and the need for active operation, which seriously hinders the application and development of solar-blind ultraviolet detection technology in passive working environments such as ultra-high voltage power equipment status monitoring. In order to give full play to the solar-blind ultraviolet detection capability of gallium oxide, a passive multi-mode interference optical waveguide structure is adopted, and the photoinduced refractive index change effect is used to transfer the refractive index change caused by photogenerated carriers as the offset of the multi-mode interference self-image point position, thereby affecting the output light intensity of the device, and realizing passive all-optical solar-blind ultraviolet detection. Summary of the invention

[0005] In order to solve the above problems, the present invention provides an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide and a preparation method thereof.

[0006] The first object of the present invention is to provide an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide, which includes an input straight waveguide, an input tapered waveguide, a multimode interference region, an output tapered waveguide and an output straight waveguide in sequence along the propagation direction of light; The length and width of the input straight waveguide are equal to that of the output straight waveguide; the length and width of the input tapered waveguide are equal to that of the output tapered waveguide; The input straight waveguide, input tapered waveguide, multimode interference region, output tapered waveguide and output straight waveguide are a substrate and a gallium oxide optical waveguide layer from bottom to top in the vertical direction; the thickness of the substrate is 0.2~1mm, and the thickness of the gallium oxide optical waveguide layer is 0.3~2μm.

[0007] Preferably, the length of the input straight waveguide and the output straight waveguide is 1.8~2.2mm, and the width is 2~3μm; the length of the input tapered waveguide and the output tapered waveguide is 80~150μm, and the port width of the input tapered waveguide and the output tapered waveguide connecting the multimode interference zone is 10~20μm; the length of the multimode interference zone is 3~4mm, and the width is 50~70μm.

[0008] Preferably, the length of the input straight waveguide and the output straight waveguide is 2 mm, and the width is 2.5 μm; the length of the input tapered waveguide and the output tapered waveguide is 100 μm, and the port width of the input tapered waveguide and the output tapered waveguide connecting the multimode interference zone is 15 μm; the length of the multimode interference zone is 3.5 mm, and the width is 60 μm.

[0009] Preferably, the substrate is sapphire Al 2 O 3 Substrate.

[0010] Preferably, sapphire Al 2 O 3 The thickness of the substrate is 0.43 mm, and the thickness of the gallium oxide optical waveguide layer is 0.9 μm.

[0011] The second object of the present invention is to provide a method for preparing an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide, which specifically comprises the following steps: S1. Clean the substrate with acetone, ethanol and deionized water in sequence under ultrasonic conditions, and blow dry with nitrogen after cleaning; S2. epitaxially growing a gallium oxide thin film on the substrate; S3. depositing a chromium film on the surface of the gallium oxide film using magnetron sputtering technology; S4. Spin-coating a photoresist on the surface of the chromium film, transferring the device geometry to the photoresist through exposure and development; etching the chromium film, transferring the device pattern to the chromium film; S5. etching the gallium oxide film under the protection of the chromium film, and further transferring the pattern to the gallium oxide film to obtain a gallium oxide optical waveguide layer; S6. Remove the chromium film to obtain an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide.

[0012] Preferably, step S2 uses metal organic chemical vapor deposition to perform epitaxial growth.

[0013] Preferably, the etching in steps S4 and S5 is performed using a reactive ion etcher.

[0014] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) The all-optical day-blind ultraviolet detector provided by the present invention realizes light detection by utilizing the change of the self-image point of multi-mode interference, without converting the optical signal into an electrical signal, and has a passive working function; (2) Compared with the traditional photoelectric detection technology, the detector utilizes the principle of photoinduced refractive index change and does not involve the drift motion of carriers, so the signal-to-noise ratio is very high; (3) The all-optical detector realizes light detection based on a planar optical waveguide and does not require a metal electrode, so the all-optical detector has a simple structure and is easy to implement.

[0015] In summary, the present invention provides an all-optical solar-blind ultraviolet detector based on gallium oxide optical waveguide, which solves the problem of passive detection in the solar-blind ultraviolet band and has the advantage of high signal-to-noise ratio. Solar-blind ultraviolet rays are used to irradiate gallium oxide materials to generate photogenerated carriers, thereby affecting the material band structure and modulating the material refractive index. At the same time, a multi-mode interference optical waveguide structure is used to reflect the change in the material refractive index as an offset of the self-image point, thereby changing the output light intensity, thereby realizing passive all-optical solar-blind ultraviolet detection, and alleviating the low signal-to-noise ratio caused by the background noise of the photodetector, thereby improving the stability of detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the overall structure of an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide provided according to an embodiment of the present invention.

[0017] Figure 2 1 is a schematic top view of a gallium oxide optical waveguide layer of an all-optical solar-blind ultraviolet light detector based on a gallium oxide optical waveguide provided according to an embodiment of the present invention.

[0018] Figure 3 The present invention is a flow chart of a process for preparing an all-optical solar-blind ultraviolet light detector based on a gallium oxide optical waveguide according to an embodiment of the present invention.

[0019] Figure 4 The refractive index change of the gallium oxide optical waveguide layer provided by the embodiment of the present invention is caused by irradiation of solar-blind ultraviolet light.

[0020] Figure 5 This is a light field transmission simulation diagram of the all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide provided according to an embodiment of the present invention when it is not irradiated by solar-blind ultraviolet light.

[0021] Figure 6 This is a light field transmission simulation diagram of an all-optical solar-blind ultraviolet light detector based on a gallium oxide optical waveguide provided according to an embodiment of the present invention when irradiated with solar-blind ultraviolet light.

[0022] Reference numerals: 1. Gallium oxide optical waveguide layer; 2. Substrate; 3. Input straight waveguide; 4. Input tapered waveguide; 5. Multimode interference area; 6. Output tapered waveguide; 7. Output straight waveguide. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0025] The present invention provides an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide, which comprises an input straight waveguide, an input tapered waveguide, a multi-mode interference region, an output tapered waveguide and an output straight waveguide in sequence along the propagation direction of light; The length and width of the input straight waveguide are equal to that of the output straight waveguide; the length and width of the input tapered waveguide are equal to that of the output tapered waveguide; The input straight waveguide, input tapered waveguide, multimode interference region, output tapered waveguide and output straight waveguide are vertically composed of substrate and gallium oxide optical waveguide layer from bottom to top; the thickness of the substrate is 0.2~1mm, and the thickness of the gallium oxide optical waveguide layer is 0.3~2μm; Specifically, the length of the input straight waveguide and the output straight waveguide is 1.8-2.2 mm, and the width is 2-3 μm; the length of the input tapered waveguide and the output tapered waveguide is 80-150 μm, and the port width of the input tapered waveguide and the output tapered waveguide connecting the multimode interference region is 10-20 μm; the length of the multimode interference region is 3-4 mm, and the width is 50-70 μm; In a specific embodiment, the length of the input straight waveguide and the output straight waveguide is 2 mm and the width is 2.5 μm; the length of the input tapered waveguide and the output tapered waveguide is 100 μm, and the port width of the input tapered waveguide and the output tapered waveguide connecting the multimode interference region is 15 μm; the length of the multimode interference region is 3.5 mm and the width is 60 μm; Specifically, the substrate is sapphire Al 2 O 3 , a single crystal substrate oriented to the (0001) crystal plane with a thickness of 0.2~1mm; the gallium oxide optical waveguide layer is β-phase gallium oxide with a thickness of 0.3~2μm.

[0026] In a specific embodiment, sapphire Al 2 O 3The thickness of the substrate is 0.43 mm, and the thickness of the gallium oxide optical waveguide layer is 0.9 μm.

[0027] The method for preparing the above-mentioned all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide specifically comprises the following steps: S1. Clean the substrate with acetone, ethanol and deionized water in sequence under ultrasonic conditions, and blow dry with nitrogen after cleaning; S2. epitaxially growing a gallium oxide thin film on the substrate; S3. depositing a chromium film on the surface of the gallium oxide film using magnetron sputtering technology; S4. Spin-coating a photoresist on the surface of the chromium film, transferring the device geometry to the photoresist through exposure and development; etching the chromium film, transferring the device pattern to the chromium film; S5. etching the gallium oxide film under the protection of the chromium film, and further transferring the pattern to the gallium oxide film to obtain a gallium oxide optical waveguide layer; S6. Remove the chromium film to obtain an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide; Specifically, step S2 uses metal organic chemical vapor deposition to perform epitaxial growth; Specifically, the thickness of the chromium film deposited in step S3 is 150-250 nm; Specifically, in step S4, etching is performed using a reactive ion etcher, and the thickness of the photoresist is 0.8-1.2 μm; Specifically, the etching in step S5 is performed using a reactive ion etcher.

[0028] Brief description of the principle of the present invention: The all-optical solar-blind ultraviolet detector based on gallium oxide optical waveguide provided by the present invention adopts multi-mode interference (MMI) technology. The optical waveguide structure is composed of a sapphire substrate, a gallium oxide core layer, and an air upper cladding layer in sequence. The signal light transmitted by the single-mode optical fiber is input into the input straight waveguide by end-face coupling, and is transmitted to the input tapered waveguide in the form of a basic mode. After the tapered waveguide forms a mode matching, it continues to be transmitted to the multi-mode interference region to generate a multi-mode interference and scattered light field, thereby reducing the light energy density. After the signal light propagates for a certain length in the multi-mode interference region, a self-image of the signal light basic mode light field is formed, and the light energy is thus converged to the highest value again, and continues to be transmitted to the output tapered waveguide and the output straight waveguide in sequence, and finally output by another single-mode optical fiber through end-face coupling. After the gallium oxide optical waveguide layer absorbs the energy of the solar-blind ultraviolet light, it accumulates non-equilibrium photogenerated carriers inside and fills the energy band. Since the refractive index of the material responds to the change of the energy band structure, the refractive index of the gallium oxide core layer is disturbed, so that the interference conditions of the multimode interference area change, the position of the self-image point shifts, and the light energy received at the original output tapered waveguide position decreases, thereby realizing light detection. The present invention has the following characteristics: First, the all-optical solar-blind ultraviolet light detector provided by the present invention realizes light detection by using the change of the self-image point of multimode interference, without converting the optical signal into an electrical signal, and has a passive working function; second, compared with the traditional photoelectric detection technology, the detector uses the principle of light-induced refractive index change, does not involve the drift motion of carriers, and thus has a high signal-to-noise ratio; third, the all-optical detector realizes light detection based on a planar optical waveguide, and does not require a metal electrode, so the structure of the all-optical detector is simple and easy to realize.

[0029] Example 1 See also Figure 1 This embodiment provides an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide, which includes a substrate 2 and a gallium oxide optical waveguide layer 1 from bottom to top in the vertical direction; the gallium oxide optical waveguide layer 1 includes an input straight waveguide 3, an input tapered waveguide 4, a multimode interference region 5, an output tapered waveguide 6 and an output straight waveguide 7 in sequence along the propagation direction of light; The input straight waveguide 3 and the output straight waveguide 7 have the same structure and length L 1 2mm, width W 1 The input tapered waveguide 4 and the output tapered waveguide 6 have the same structure and a length of L 2 The port width W of the input tapered waveguide 4 and the output tapered waveguide 6 connecting the multimode interference region 5 is 100 μm. 2 are 15 μm; the length L of the multimode interference zone 5 3 3.5mm, width W 3 60μm; Substrate 2 is sapphire Al 2 O 3Substrate; thickness is 0.43mm; the gallium oxide optical waveguide layer is β-phase gallium oxide, with a thickness of 0.9μm.

[0030] The preparation method is as follows Figure 3 As shown, the specific steps include: S1. The substrate 2 is cleaned in sequence using acetone, ethanol, and deionized water under ultrasonic conditions, and then dried with high-purity nitrogen gas; S2. epitaxially growing a 0.9 μm thick gallium oxide film on substrate 2 using a metal organic chemical vapor deposition device; S3. Depositing a 200 nm thick chromium film on the surface of the gallium oxide film using magnetron sputtering technology; S4. Spin-coating a layer of BP212 photoresist with a thickness of 1 μm on the surface of the chromium film; transferring the device geometry to the BP212 photoresist by exposure and development using a UV photolithography machine; etching the chromium film under the protection of the BP212 photoresist pattern using a reactive ion etcher to transfer the device pattern to the chromium film; S5. Using a reactive ion etcher to etch the gallium oxide film under the protection of the chromium film, the pattern is further transferred to the gallium oxide film to obtain a gallium oxide optical waveguide layer 1; S6. Use metal etching solution to completely remove the remaining chromium film to obtain an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide.

[0031] Example 2 This embodiment provides an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide, which includes an input straight waveguide, an input tapered waveguide, a multi-mode interference region, an output tapered waveguide and an output straight waveguide in sequence along the propagation direction of light; and a substrate and a gallium oxide optical waveguide layer from bottom to top in the vertical direction; The input straight waveguide and the output straight waveguide have the same structure, with a length of 2mm and a width of 3μm; the input tapered waveguide and the output tapered waveguide have the same structure, with a length of 120μm, and the port widths of the input tapered waveguide and the output tapered waveguide connecting the multimode interference zone are both 15μm; the multimode interference zone has a length of 3.5mm and a width of 55μm; The substrate is sapphire Al 2 O 3 Substrate; thickness is 0.7 mm; the gallium oxide optical waveguide layer is β-phase gallium oxide, with a thickness of 0.5 μm.

[0032] The preparation method is the same as Example 1.

[0033] Example 3 This embodiment provides an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide, which includes an input straight waveguide, an input tapered waveguide, a multi-mode interference region, an output tapered waveguide and an output straight waveguide in sequence along the propagation direction of light; and a substrate and a gallium oxide optical waveguide layer from bottom to top in the vertical direction; The input straight waveguide and the output straight waveguide have the same structure, with a length of 1.8 mm and a width of 3 μm; the input tapered waveguide and the output tapered waveguide have the same structure, with a length of 100 μm, and the port widths of the input tapered waveguide and the output tapered waveguide connected to the multimode interference zone are both 20 μm; the multimode interference zone has a length of 4 mm and a width of 60 μm; The substrate is sapphire Al 2 O 3 Substrate; thickness is 0.7 mm; the gallium oxide optical waveguide layer is β-phase gallium oxide, with a thickness of 2 μm.

[0034] The preparation method is the same as Example 1.

[0035] The optical property response of the gallium oxide optical waveguide layer of the detector prepared by the present invention to solar-blind ultraviolet light irradiation was tested. The refractive index dispersion curve of the gallium oxide optical waveguide layer in the dark and solar-blind ultraviolet light irradiation state was characterized by using an ellipsometer. The test results are shown in the attached Figure 4 shown. Figure 4 It is shown that the refractive index of the gallium oxide optical waveguide layer drifts under the irradiation of solar-blind ultraviolet light, and the drift amplitude in the long-wave direction increases, which proves the theoretical feasibility of the present application.

[0036] The simulation calculation of the transmission of signal light in the embodiment under the conditions of darkness and solar-blind ultraviolet light irradiation is shown in the attached figure. Figure 5 and attached Figure 6 As shown in the attached Figure 5 In the dark state, the input optical signal of the embodiment device is input through the input waveguide of the device and transmitted through the device, and then output from the output waveguide of the device with the maximum optical field intensity. Figure 6 In the device under the solar-blind ultraviolet radiation state, the self-image point of the signal light transmitted in the multi-mode interference region of the embodiment device is offset, and after transmission through the device, only part of the light field intensity is output by the device output waveguide, thereby realizing the full-light solar-blind ultraviolet detection function. This detection process has no external electric field, so it has the characteristics of passive operation.

[0037] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0038] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide, characterized in that: The light propagation direction includes an input straight waveguide, an input tapered waveguide, a multi-mode interference region, an output tapered waveguide and an output straight waveguide in sequence; The length and width of the input straight waveguide are equal to that of the output straight waveguide; the length and width of the input tapered waveguide are equal to that of the output tapered waveguide; The input straight waveguide, input tapered waveguide, multimode interference region, output tapered waveguide and output straight waveguide are a substrate and a gallium oxide optical waveguide layer from bottom to top in the vertical direction; the thickness of the substrate is 0.2~1mm, and the thickness of the gallium oxide optical waveguide layer is 0.3~2μm.

2. The all-optical solar-blind ultraviolet detector based on gallium oxide optical waveguide according to claim 1, characterized in that: The length of the input straight waveguide and the output straight waveguide is 1.8~2.2mm, and the width is 2~3μm; the length of the input tapered waveguide and the output tapered waveguide is 80~150μm, and the port width of the input tapered waveguide and the output tapered waveguide connecting the multimode interference zone is 10~20μm; the length of the multimode interference zone is 3~4mm, and the width is 50~70μm.

3. The all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide according to claim 1, characterized in that: The length of the input straight waveguide and the output straight waveguide is 2 mm, and the width is 2.5 μm; the length of the input tapered waveguide and the output tapered waveguide is 100 μm, and the port width of the input tapered waveguide and the output tapered waveguide connecting the multimode interference zone is 15 μm; the length of the multimode interference zone is 3.5 mm, and the width is 60 μm.

4. The all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide according to claim 1, characterized in that: The substrate is a sapphire Al2O3 substrate.

5. The all-optical solar-blind ultraviolet detector based on gallium oxide optical waveguide according to claim 4, characterized in that: The thickness of the sapphire Al2O3 substrate is 0.43 mm, and the thickness of the gallium oxide optical waveguide layer is 0.9 μm.

6. A method for preparing an all-optical solar-blind ultraviolet detector based on a gallium oxide optical waveguide according to any one of claims 1 to 5, characterized in that: The specific steps include: S1. Clean the substrate with acetone, ethanol and deionized water in sequence under ultrasonic conditions, and then dry it with nitrogen gas; S2. epitaxially growing a gallium oxide thin film on the substrate; S3. depositing a chromium film on the surface of the gallium oxide film using magnetron sputtering technology; S4. Spin-coating a photoresist on the surface of the chromium film, and transferring the device geometry to the photoresist through exposure and development; etching the chromium film to transfer the device pattern to the chromium film; S5. etching the gallium oxide film under the protection of the chromium film, and further transferring the pattern to the gallium oxide film to obtain a gallium oxide optical waveguide layer; S6. Remove the chromium film to obtain an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide.

7. The method for preparing an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide according to claim 6, characterized in that: The step S2 uses metal organic chemical vapor deposition to perform epitaxial growth.

8. The method for preparing an all-optical solar-blind ultraviolet light detector based on gallium oxide optical waveguide according to claim 7, characterized in that: The etching in steps S4 and S5 is performed using a reactive ion etcher.

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