Light field detector and light field imager based on micro-nano optical structure

Abstract

The invention provides a light field detector based on a micro-nano optical structure and a light field imager. The light field detector comprises a substrate, an active region, an electrode and the micro-nano optical structure, wherein the micro-nano optical structure is prepared on the surface of the active region and / or the electrode; the micro-nano optical structure prepared in the active area is used for regulating and controlling the light field distribution of incident light in the active area, and the micro-nano optical structure prepared on the surface of the electrode is used for regulating and controlling the transmittance of the incident light, so that the light field detector generates different adjustable and controllable light responses to the incident light carrying different optical information under the driving of different voltages. Therefore, the adjustable reconstruction of the multi-dimensional optical information of the incident light can be realized. The optical information comprises wavelength information, optical power information, optical polarization information and optical phase information.

Description

Technical Field

[0001] The present disclosure relates to the fields of optoelectronics and semiconductor technologies, and particularly to an optical field detector and an optical field imager based on a micro-nano optical structure. Background Art

[0002] With the rapid development of information technology, people's demand for optical field sensing has been increasing day by day. The optical field contains information in multiple dimensions such as intensity, polarization, frequency, and phase. Among them, spectral detection and polarization detection contain information such as the material composition and surface topography of an object, and have great application value in the fields of optical communication, remote sensing, industrial inspection, medical diagnosis, chemical analysis, environmental protection, etc. However, traditional photodetectors are limited to measuring light intensity, and current polarization and spectral detectors can usually only measure the intensity and polarization at a fixed wavelength or the intensity and wavelength information under uniform polarization. In short, in many natural scenes, the optical field may carry arbitrary polarization and intensity changes in a wide spectral range, and existing detectors are difficult to detect such high-dimensional information. The current solutions to the above-mentioned technical problems are mainly based on the principles of traditional spectrometers and polarization detectors, and wavelength or polarization sensitive elements are constructed and integrated in space. For example, different photonic crystal structures are integrated on a traditional spectrometer, additional filters are integrated on a traditional polarimeter, or hundreds of measurements are performed in time to expand the spectral and polarization detection capabilities of existing devices. However, this method often leads to additional optical elements and testing steps, resulting in a large system volume, a long detection time, and higher costs, and is powerless to realize a small-volume, fast-response high-dimensional optical field detector in the future. In recent years, great progress has been made in the miniaturization of traditional spectrometers. By using computational spectroscopy technology, an optoelectronic detector with an adjustable broadband spectral response is used, combined with excellent algorithms, to reconstruct spectral signals and images, reducing the volume of the spectrometer. However, the current miniaturized computational spectrometers do not have the ability to detect polarization, and still need additional optical elements to introduce polarization sensitive components, increasing the system complexity; on the other hand, existing technical solutions are highly sensitive to material growth conditions, layer thickness, interface contact, and environmental factors, resulting in challenges in large-scale applications. Summary of the Invention

[0003] In view of this, in order to at least partially solve at least one of the above-mentioned technical problems, the present disclosure provides an optical field detector and an optical field imager based on a micro-nano optical structure.

[0004] To achieve the above object, the technical solution of the present disclosure is as follows:

[0005] Embodiments of one aspect of the present disclosure provide an optical field detector based on a micro-nano optical structure, including: a substrate, an active region, an electrode, and a micro-nano optical structure; wherein, the micro-nano optical structure is fabricated on the surface of the active region and / or the electrode; the micro-nano optical structure fabricated on the active region is used to regulate the optical field distribution of incident light in the active region, and the micro-nano optical structure fabricated on the electrode surface is used to regulate the transmittance of incident light, so that the optical field detector generates different adjustable optical responses to incident light carrying different optical information under the drive of different voltages, to achieve adjustable reconstruction of multi-dimensional optical information of the incident light; the optical information includes wavelength information, optical power information, optical polarization information, and optical phase information. The optical information may also include spin information or mode information.

[0006] According to an embodiment of the present disclosure, the active region generates a specific broad-spectrum response to light with an incident light wavelength falling within the range of 10 nm to 10 μm; when the micro-nano optical structure is fabricated on the active region, the incident light can enter from the substrate or electrode side; when the micro-nano optical structure is fabricated on the electrode surface, the electrode is a transparent electrode, so that the incident light can enter from the electrode side.

[0007] According to an embodiment of the present disclosure, the micro-nano optical structure is an anisotropic nano-column array, and the shape of the horizontal cross-section of the nano-column includes an ellipse, a circle, a polygon, or an irregular shape; the nano-column array includes a plurality of nano-columns with different cross-sectional areas, and / or a plurality of nano-columns with different spacings, and / or a plurality of nano-columns with different cross-sectional shapes; the horizontal cross-sectional area of each nano-column is 1 nm 2 -1000 μm 2 , the spacing between nano-columns is 1 nm - 1000 μm, the height of nano-columns is 1 nm - 1000 μm, and the array forms formed by nano-columns include photonic crystal structures, metasurface structures, and surface plasmon structures.

[0008] According to an embodiment of the present disclosure, the micro-nano optical structure is an anisotropic nano-pore array, and the cross-section of the nano-pore includes an ellipse, a circle, a polygon, and / or an irregular shape; the nano-pore array includes a plurality of nano-pores with different cross-sectional areas, and / or a plurality of nano-pores with different spacings, and / or a plurality of nano-pores with different cross-sectional shapes; the area of each nano-pore is 1 nm 2 -1000 μm 2 , the spacing between nano-pores is 1 nm - 1000 μm, the depth of nano-pores is 1 nm - 1000 μm, and the array forms formed by nano-pores include photonic crystal structures, metasurface structures, and surface plasmon structures.

[0009] According to an embodiment of the present disclosure, the micro-nano optical structure is an anisotropic annular column array, and the cross-sectional shape of the annular column includes a circular ring, an elliptical ring, a polygonal ring, and / or an irregular ring; the annular column array includes a plurality of annular columns with different cross-sectional areas, and / or a plurality of annular columns with different spacings, and / or a plurality of annular columns with different cross-sectional shapes, and the area of each nano-ring is 1 nm 2 -1000 um 2 , the spacing between the nano-pores is 1 nm - 1000 um, the height of the nano-ring is 1 nm - 1000 um, and the array forms formed by the annular nano-columns include a photonic crystal structure, a metasurface structure, and a surface plasmon structure.

[0010] According to an embodiment of the present disclosure, the micro-nano optical structure is an anisotropic grating array, and the grating array includes a plurality of array units with different cross-sectional areas, and / or a plurality of array units with different spacings, and / or a plurality of array units with different orientations, and the cross-sectional area of each array unit is 1 nm 2 -1000 um 2 , the spacing between the array units is 1 nm - 1000 um, and the unit height is 1 nm - 1000 um.

[0011] According to an embodiment of the present disclosure, the active region is configured as a light-detecting semiconductor epitaxial structure having a wide spectral response and an adjustable light response curve with the change of the external bias voltage.

[0012] According to an embodiment of the present disclosure, the active region includes, from bottom to top, a first N-type semiconductor material layer, a first unintentionally doped semiconductor material layer, a P-type semiconductor material layer, a second unintentionally doped semiconductor material layer, and a second N-type semiconductor material layer.

[0013] According to an embodiment of another aspect of the present disclosure, there is provided a light field imager based on the light field detector array described in any one of the above, wherein the light field detector array is implemented by controlling each light field detector unit individually through an external electrical circuit, or by controlling multiple light field detector units in parallel, in series, or in a combination of series and parallel, to achieve spectral detection, analysis, and spectral imaging of a spectrum within a certain wavelength range, including the information of the linear polarization degree and the circular polarization degree of light. Description of the Drawings

[0014] Through the following description of the embodiments of the present disclosure with reference to the drawings, the above and other objects, features, and advantages of the present disclosure will become clearer. In the drawings:

[0015] Figure 1 It is a schematic diagram of the light field detector based on the micro-nano optical structure according to the embodiment of the present disclosure.

[0016] Figure 2Schematic structural diagram of a light field detector based on a micro-nano optical structure according to an embodiment of the present disclosure.

[0017] Figure 3 Schematic structural diagram of another light field detector based on a micro-nano optical structure according to an embodiment of the present disclosure.

[0018] Figure 4 Schematic diagram of the working principle of a light field detector based on a micro-nano optical structure according to an embodiment of the present disclosure. Detailed implementation manners

[0019] The present disclosure provides a light field detector and a light field imager based on a micro-nano optical structure, which can achieve a balance among miniaturization, integration, single measurement, full spectrum, scalable growth, and stability, and realize the implementation of a portable and high-dimensional light field imaging system. For example, a micro-nano optical structure with specific polarization sensitivity can be etched on the active region of a micro-spectrometer with a bias-tunable light response characteristic to form a light field detector sensitive to high-dimensional light field information such as spectrum and polarization and a light field imager based on a detector array. First, the epitaxial structure of the active region enables the device to have a wide response spectrum, and enables the detection ability of the device to light of different wavelengths to change under different bias conditions, thereby changing the intensity and characteristics of photocurrent competition and resulting in an adjustable spectral response curve. Second, by etching, a specific micro-nano optical structure is formed in the active region of the photodetector, enabling the device to have different responses to different polarized lights. Therefore, through a deep neural network calculation and reconstruction algorithm, the spectral and polarization response curves obtained based on different biases are trained. Based on this, when an unknown light containing high-dimensional light field information is incident, the spectral and polarization response curves obtained based on different biases can be used to compare and reconstruct with the curves obtained by training, so as to finally realize the reconstruction of high-dimensional light field data. Furthermore, a single high-dimensional light field detector (a single device can form a single-pixel image) is fabricated in an array and interconnected in series and parallel to achieve the function of single-shot high-resolution high-dimensional light field imaging. The realization of this function lays a foundation for high-efficiency, low-cost, and fast high-dimensional light field analysis and imaging.

[0020] Micro-nano optical structures are functional structures with micron- or nano-scale feature sizes arranged in a specific manner. A high-dimensional light detector is a broadband photodetector array with different spectral responses and polarization responses, combined with superior algorithms. Through a single measurement by a single device, it can comprehensively characterize a high-dimensional light field with arbitrarily varying polarization and intensity within a broadband spectral range. A high-dimensional light field imager is an instrument that combines the functions of imaging and multi-dimensional analysis of light field information. It can simultaneously obtain multi-dimensional optical information such as the spatial information (position, shape, etc.) of an object and the light intensity, spectral, and polarization information (optical properties of materials). Different from traditional multi-dimensional light detectors (which can only measure the multi-dimensional information of a single point of the light field or require multiple measurements to achieve different-dimensional light field analysis), a high-dimensional light field imager can obtain multi-dimensional data of the light field in a single measurement of the entire scene, so it can be used to identify and distinguish different materials or substances.

[0021] Regarding polarization and spectral separation detectors: Usually, independent optical components are used to measure polarization and spectral information. Polarization information is usually obtained through a series of polarizers, wave plates, or polarization filters, while spectral information is obtained through a spectrometer or grating. Both can be combined with a CCD or CMOS sensor to complete the measurement. Disadvantages include: Complex structure. Since multiple independent components are required to obtain information of different attributes, such systems are usually large in size and difficult to miniaturize. Limited accuracy. Due to the complex coupling between the optical path and components, the system often faces accuracy losses when measuring composite information. High cost. High-quality optical and spectral components are usually expensive, resulting in a relatively high overall cost of the system.

[0022] Regarding nanostructures and metamaterials: Materials that control light at the nanoscale, such as metal nanoparticles, photonic crystals, and metamaterials, etc. These structures can manipulate the phase, amplitude, and polarization of light to achieve responses to different light attributes. Disadvantages include: High manufacturing difficulty. The manufacture of high-precision nanostructures requires extremely high process technologies, including electron beam lithography, nanoimprinting, etc., and the manufacturing is complex and expensive. Poor stability and consistency. It is difficult to control the stability of materials and their consistency in large-scale production, and there are challenges in realizing samples with uniform and reliable characteristics. Limited applicability. Metamaterials can only work effectively within a specific wavelength range, which limits their use in wide-spectrum applications.

[0023] The current methods for solving the problems in the existing technologies are mainly based on the principles of traditional spectrometers and polarization detectors, constructing and integrating wavelength or polarization sensitive elements in space. For example, integrating different photonic crystal structures on traditional spectrometers, integrating additional filters on traditional polarimeters, or performing hundreds of measurements over time to expand the spectral and polarization detection capabilities of existing devices. However, this method often leads to additional optical elements and testing steps, resulting in a huge system volume, a long detection time, and a higher cost, and is powerless to realize future small-volume, fast-response high-dimensional light field detectors.

[0024] In recent years, great progress has been made in the miniaturization of traditional spectrometers. Using computational spectroscopy technology, with a photodetector with an adjustable broadband spectral response, combined with superior algorithms, to reconstruct spectral signals and images, reducing the volume of the spectrometer. However, the current miniaturized computational spectrometers do not have the ability to detect polarization and still require additional optical elements to introduce polarization sensitive components, increasing the system complexity; on the other hand, the existing technical solutions are highly sensitive to material growth conditions, layer thickness, interface contact, and environmental factors, leading to challenges in large-scale applications.

[0025] The current relevant representative research work in this field includes:

[0026] (1) Spatial and frequency dispersion encoding of optical interfaces realized by multilayer film structures (Fan, Y., Huang, W., Zhu, F. et al. Dispersion-assisted high-dimensional photodetector. Nature 630, 77–83 (2024)).

[0027] Principle: Through a multilayer film structure, using the spatial dispersion and frequency dispersion characteristics of the optical interface to encode high-dimensional information, and then combining deep learning for decoding, using a single device to achieve high-precision detection of high-dimensional light field information through a single measurement.

[0028] Disadvantages: 1) Combining the thin film with a microlens array and an imaging sensor array in a "sandwich" manner is essentially still the integration of discrete devices, increasing the system complexity and cost; 2) The introduction of the multilayer film structure will inevitably reduce the detected light intensity, reducing the device responsivity and detection sensitivity; 3) It is difficult to achieve a multilayer film structure with a large bandwidth response in a large scale range. Therefore, it is very difficult to realize a full-spectrum high-dimensional light field imager using this technical solution.

[0029] (2)Metasurface-enabled broadband multidimensional photodetectors (Jiang, H., Chen, Y., Guo, W. et al. Metasurface-enabled broadband multidimensional photodetectors. Nature Communications 15, 8347 (2024).).

[0030] Principle: By integrating a metasurface structure on the surface of a graphene photodetector, spectral resolution with a 0.5-μm discrimination and circular polarization detection are achieved.

[0031] Disadvantages: 1) Limited linear dynamic range: The photoabsorption layer of two-dimensional materials is usually thin (only a few nanometers), and the number of photo-generated carriers is small, resulting in a limited linear dynamic range (LDR) of the detector. This may lead to signal saturation under strong light illumination and weak signals under weak light illumination, affecting the accuracy of spectral data. 2) Poor material homogeneity and reproducibility, and difficulty in large-scale array production: Current preparation methods of two-dimensional materials (such as CVD, mechanical exfoliation) may lead to poor material homogeneity, such as uneven thickness, grain boundary defects, uneven doping, etc. 3) Low spectral resolution and only two circular polarization states can be resolved: Due to the simplicity of the material structure and the limitation of the high wavelength requirements of the metasurface design, the spectral and polarization resolution capabilities of this device are poor.

[0032] Therefore, this application proposes a light field detector based on a micro-nano optical structure, specifically a high-dimensional light field detector and a high-dimensional light field imager based on a micro-spectrometer with a micro-nano optical structure active region or a micro-nano optical structure integrated on the surface of the top transparent electrode. Etch a micro-nano optical structure sensitive to light information such as specific polarization, phase, intensity, spin, longitudinal mode / transverse mode, etc. on the active region of the micro-spectrometer with a bias-tunable light response characteristic. The micro-nano optical structure includes periodically arranged nanocylinders with different diameters (or other shaped cylinders, nanopores, nanorings, grating structures may also be used), and the size and spacing of the nanostructures match the wavelength of light, or replace the electrode on the top of the device with a transparent electrode and integrate a micro-nano optical structure on the electrode that responds to light information such as different polarization, phase, intensity, spin, longitudinal mode / transverse mode, etc. The micro-nano optical structure is anisotropic, enabling the device to produce different responses to different polarized lights. Finally, through a reconstruction algorithm, based on the spectral and polarization response curves under different biases, the reconstruction of spectral and polarization data and images can be achieved. For the working principle, see Figure 4As shown, a photodetector is adopted that has an active region with a special polarization-sensitive micro-nano optical structure or a micro-nano optical structure on the surface of a transparent electrode and controls the spectral response through a bias voltage. The intensity, wavelength, polarization, and other spectral and polarization information of the incident light field can be reconstructed through a single detection. When performing photoresponse calculation and reconstruction, for example, it can be based on deep neural network modeling of the device current-voltage (I-V) curve data. 1. First, the device response obtained through I-V measurement is used as the input signal. This signal is processed by a large number of neurons, and its non-linear characteristics are captured through an activation function. 2. A residual block containing three fully connected layers is used to effectively prevent gradient disappearance, thereby extracting deeper feature information. 3. The output layer converts the processed data into the final spectral and polarization information. For example, the entire model can be trained on a GPU in a small batch (e.g., batch size of 10) manner, with an initial learning rate of 1×10 -4 , and weight decay is performed after 100 iterations, and finally converges at 200 iterations. Through this method, the deep neural network can accurately learn the complex mapping relationship between the device I-V curve and the spectrum and polarization, and achieve high-precision spectral reconstruction. Thus, based on the spectral response curves under different bias voltages, spectral data and images can be reconstructed.

[0033] To make the objectives, technical solutions, and advantages of the present disclosure more clear and understandable, the following further details the present disclosure in conjunction with specific embodiments and with reference to the accompanying drawings.

[0034] In an embodiment of the present disclosure, in combination with Figures 1 to 3 as shown, a light field detector based on a micro-nano optical structure is provided, including: a substrate, an active region, an electrode, and a micro-nano optical structure;

[0035] Among them, the micro-nano optical structure is fabricated on the active region and / or the surface of the electrode; the micro-nano optical structure fabricated on the active region is used to regulate the light field distribution of the incident light in the active region, and the micro-nano optical structure fabricated on the surface of the electrode is used to regulate the transmittance of the incident light, so that the light field detector generates different adjustable photoresponses to incident light carrying different optical information under the drive of different voltages to achieve adjustable reconstruction of the multi-dimensional optical information of the incident light; the optical information includes wavelength information, optical power information, light polarization information, and light phase information.

[0036] According to an embodiment of the present disclosure, the active region generates a specific broad spectral response to light with an arbitrary wavelength range within the range of 10 nm to 10 μm, without including the complete spectral range of 10 nm to 10 μm; when the micro-nano optical structure is fabricated on the active region, the incident light can enter from the substrate or electrode side; when the micro-nano optical structure is fabricated on the surface of the electrode, the electrode is a transparent electrode, so that the incident light can enter from the electrode side.

[0037] According to embodiments of the present disclosure, the material for preparing the substrate is selected from semiconductors or quartz glass including sapphire, silicon, germanium, silicon carbide, gallium oxide, boron nitride, diamond, aluminum nitride, gallium nitride, gallium arsenide, and indium phosphide, or a material having transparency characteristics for light within the wavelength range from deep ultraviolet light to infrared light. The material for preparing the electrode is selected from Ti, Al, Ni, Au, Cr, Pt, or a combination thereof. The material for preparing the transparent electrode is, for example, a transparent electrode such as ITO. According to embodiments of the present disclosure, the optical information further includes spin information or mode information (for example, the optical field mode is TE, TM, or TEM mode).

[0038] According to embodiments of the present disclosure, the micro-nano optical structure can be an anisotropic nano-column array. The shape of the horizontal cross-section of the nano-column includes an ellipse, a circle, a polygon, or an irregular shape; the nano-column array includes multiple nano-columns with different cross-sectional areas, and / or multiple nano-columns with different spacings, and / or multiple nano-columns with different cross-sectional shapes; the horizontal cross-sectional area of each nano-column is 1 nm 2 -1000 μm 2 , the spacing between the nano-columns is 1 nm - 1000 μm, the height of the nano-columns is 1 nm - 1000 μm, and the array forms formed by the nano-columns include a photonic crystal structure, a metasurface structure, and a surface plasmon structure.

[0039] According to embodiments of the present disclosure, the micro-nano optical structure can be an anisotropic nano-pore array. The cross-section of the nano-pore includes an ellipse, a circle, a polygon, and / or an irregular shape; the nano-pore array includes multiple nano-pores with different cross-sectional areas, and / or multiple nano-pores with different spacings, and / or multiple nano-pores with different cross-sectional shapes; the area of each nano-pore is 1 nm 2 -1000 μm 2 , the spacing between the nano-pores is 1 nm - 1000 μm, the depth of the nano-pores is 1 nm - 1000 μm, and the array forms formed by the nano-pores include a photonic crystal structure, a metasurface structure, and a surface plasmon structure.

[0040] According to embodiments of the present disclosure, the micro-nano optical structure can be an anisotropic annular column array. The cross-sectional shape of the annular column includes a ring, an elliptical ring, a polygonal ring, and / or an irregular ring; the annular column array includes multiple annular columns with different cross-sectional areas, and / or multiple annular columns with different spacings, and / or multiple annular columns with different cross-sectional shapes, and the area of each nano-ring is 1 nm 2 -1000 μm 2, the spacing between the nanopores is 1 nm - 1000 μm, the height of the nanoring is 1 nm - 1000 μm, and the array forms formed by the annular nanocolumns include a photonic crystal structure, a metasurface structure, and a surface plasmon structure.

[0041] According to an embodiment of the present disclosure, the micro-nano optical structure can be a grating array with anisotropy. The grating array includes a plurality of array units with different cross-sectional areas, and / or a plurality of array units with different spacings, and / or a plurality of array units with different orientations. The cross-sectional area of each array unit is 1 nm 2 - 1000 μm 2 , the spacing between the array units is 1 nm - 1000 μm, and the unit height is 1 nm - 1000 μm.

[0042] According to an embodiment of the present disclosure, the active region is configured as a light-detecting semiconductor epitaxial structure with a wide spectral response and an adjustable light response curve with the change of the external bias voltage.

[0043] According to an embodiment of the present disclosure, the active region can, for example, include a first N-type semiconductor material layer, a first unintentionally doped semiconductor material layer, a P-type semiconductor material layer, a second unintentionally doped semiconductor material layer, and a second N-type semiconductor material layer from bottom to top.

[0044] According to an embodiment of the present disclosure, a functional layer (such as a two-dimensional material, a photonic crystal layer, a metasurface, a grating, etc.) capable of optically modulating the incident light (wavelength, optical power, light polarization, light phase) can be further integrated at the lower part (under the substrate) or the top of the device, which can achieve the technical effects of spectral detection and reconstruction while expanding the application prospects.

[0045] According to an embodiment of the present disclosure, the active region of the on-chip micro-optical field detector can be configured to include at least two light-detecting epitaxial structures with different light response ranges in the vertical direction. Such as Figure 2 and Figure 3As shown, the active region includes, from bottom to top, a first N-type semiconductor material layer 2, a first unintentionally doped semiconductor material layer 3, a P-type semiconductor material layer 4, a second unintentionally doped semiconductor material layer 5, and a second N-type semiconductor material layer 6, and a first electrode 7 and a second electrode 8 are fabricated; the first N-type semiconductor material layer 2, the first undoped semiconductor material layer 3, and the P-type semiconductor material layer 4 form an n-i-p type bottom diode structure, serving as a photodetector with a first spectral response, and the P-type semiconductor material layer 4, the second undoped semiconductor material layer 5, and the second N-type semiconductor material layer 6 form a p-i-n type top diode structure, serving as a photodetector with a second spectral response. Here, i (intrinsic) in the n-i-p or p-i-n layer represents an intrinsic epitaxial layer structure, which can be a single component, or have a gradually changing component, or change in a stepped manner. Corresponding to the first undoped semiconductor material layer 4 and the second undoped semiconductor material layer 6, it can be a material with a fixed component, or a material with a gradually changing component, or a material with a stepped change. Among them, the way of component change can be gradual increase; gradual decrease; increase first and then decrease; decrease first and then increase, etc. In this photodiode, for the other epitaxial layers except the intrinsic layer, the component of each layer can be fixed or gradually changing. The way of gradual component change will change the specific photocurrent response performance of the micro-light production detector. Among them, the thickness of each graded layer can be between 0.1 nm and 5 μm. The way of gradual component change will only change the specific photocurrent response performance of the cascade photodiode, but can all meet the requirements for realizing a micro-spectrometer (that is, the response of the cascade photodiode to light of a specific wavelength changes with the bias voltage). It should be noted that the unintentionally doped layer in the cascade diode epitaxial structure can also be doped with n-type or p-type, and its doping concentration ranges from the completely undoped case to n-type doping of Al 0.6 Ga 0.4The concentration of electrons in the N layer or the concentration of holes in the p-type doped GaN layer. The above two cascaded bottom diode structures and top diode structures, that is, a group of cascaded diode epitaxial structures, for example, the bottom n-i-p type diode and the upper p-i-n type diode above it can be further stacked. An n-i-p type diode and a p-i-n type diode can be further fabricated on the p-i-n type diode in the first group of cascaded diodes to form a second group of cascaded n-i-p type / and p-i-n type diode structures. According to actual requirements, a third group, a fourth group of cascaded diode epitaxial structures can be further stacked. It should be noted that the stacking order of the n-i-p type diode and the p-i-n type diode can be reversed or changed. It should also be noted that by changing the component distribution and component composition form of each layer of material in the optoelectronic cascaded diode, their light absorption performance can be changed, such as a compositionally graded layer to achieve light absorption in a wide spectral range. Specifically, during the material epitaxial growth process, along the epitaxial direction, by gradually changing the components of the material, materials with different components correspond to absorbing the wavelength range corresponding to that material, generating a certain amount of photo-generated electron-hole pairs, and finally achieving a photocurrent response curve for a specific spectrum, providing a device basis for subsequent spectral reconstruction. In addition, based on an n-i-p type diode or a p-i-n type diode, different light responses can also be achieved under different bias voltages, thereby constructing an on-chip micro-photodetector, such as inserting a tunneling junction structure in a single diode. The tunneling junction can be inserted into any layer or the connection between any two layers in this cascaded diode, and the thickness of the tunneling junction is between 0.1 and 500 nm. The material composition of the tunneling junction is similar to the material elements surrounding the insertion position, but the component ratio is different from that of the surrounding materials.

[0046] It should also be noted that due to the cascading of two or several optoelectronic diodes, in the case of applying positive or negative voltage to the optoelectronic cascaded diode, there is always one or several optoelectronic diodes operating in one of the forward and reverse bias states, that is, at least one optoelectronic diode in this cascaded optoelectronic diode operates in the forward bias state and at least one optoelectronic diode operates in the reverse bias state, so that the leakage current of the optoelectronic cascaded diode is extremely low, having significant advantages in device stability and energy consumption, and also being beneficial to improving the spectral measurement and spectral resolution ability (i.e., spectral resolution).

[0047] The active region refers to the region where incident light is absorbed. According to the embodiments of the present disclosure, for example, the active region includes at least one photodiode epitaxial structure along the material epitaxial direction, or includes two cascaded photodiode epitaxial structures for different light response ranges. For example, based on the n-i-p type diode with wide spectral response at the bottom and the p-i-n type diode with narrow spectral response at the top of the cascaded diode structure, its working principle is as follows: First, the bottom n-i-p diode has a wide spectral response and can generate a fixed photocurrent response to light of different wavelengths; Second, the top p-i-n diode has a narrow spectral response to light and generates a photocurrent response in the opposite direction to the bottom diode. Since the two cascaded diodes generate opposite photocurrents, under different bias conditions, the energy band offset trend of the two diodes will change, thereby changing the intensity and characteristics of photocurrent competition, resulting in an adjustable spectral response curve. Therefore, through the deep neural network calculation reconstruction algorithm, the spectral response curves obtained based on different biases are trained. Based on this, when an unknown light is incident, the spectral response curves obtained based on different biases can be used to compare and reconstruct with the curves obtained through training, so as to finally realize spectral data reconstruction. Furthermore, we fabricate an array of single light field detectors or spectrometers (which can form a single-pixel image through a single device) and connect them in series and parallel to achieve the function of single-shot high-resolution spectral imaging. The realization of this function lays a foundation for high-efficiency, low-cost, rapid spectral analysis and spectral imaging. Finally, through spectral reconstruction methods, such as deep neural network modeling based on the device IV curve data, 1. First, the device response obtained through IV measurement is used as the input signal, which is processed by a large number of neurons, and its nonlinear characteristics are captured through the activation function. 2. The residual block containing three fully connected layers is used to effectively prevent gradient disappearance, so as to extract deeper feature information. 3. The output layer converts the processed data into the final spectral information. For example, the entire model can be trained in batches on the GPU, with an initial learning rate of 1×10 -4 , and weight decay is performed after hundreds of iterations, and finally converges. Through this method, the deep neural network can accurately learn the complex mapping relationship between the device IV curve and the spectrum, and achieve high-precision spectral reconstruction. Thus, based on the spectral response curves under different biases, the reconstruction of spectral data and images can be realized.

[0048] In the embodiments of the present disclosure, as Figure 2 shown, the active region is fabricated with micro-nano optical structures; the micro light field detector generates different light responses to incident light with different light information through the micro-nano optical structures under different bias drives to achieve adjustable reconstruction of light field dimension information including spectrum, polarization, etc.

[0049] In the embodiments of the present disclosure, as Figure 3As shown, when the electrode is a transparent electrode, a micro-nano optical structure can be fabricated on the surface of the transparent electrode; the micro-optical field detector generates different optical responses to incident light of different optical information through the micro-nano optical structure under different bias voltage drives, so as to achieve the controllable reconstruction of optical field dimension information including spectrum and polarization.

[0050] Specifically, as Figure 2 and Figure 3 shown, a first N-type semiconductor material layer 2 (e.g., an N-type doped GaN layer), a first unintentionally doped semiconductor material layer 3 (e.g., a gradient unintentionally doped compositionally graded layer In 0.4-0 Ga 0.6-1 N), a P-type semiconductor material layer 4 (e.g., a P-type doped GaN layer), a second unintentionally doped semiconductor material layer 5 (a gradient unintentionally doped compositionally graded layer In 0.1-0.5 Ga 0.9-0.5 N) can be successively grown on a substrate 1 (which can be any one of epitaxial substrates such as sapphire, Si, SiC, AlN, GaN, or quartz glass), and finally, a second N-type semiconductor material layer 6 (e.g., an N-type doped GaN layer) is grown on the top layer. The PIN junction with two oppositely directed compositionally graded layers with gradient unintentional doping is the reason for the wide-spectrum response with bias voltage control in this example, and the active region with different micro-nano optical structures or the micro-nano optical structures integrated on the top is the reason for polarization detection in this example. The thickness of each layer is not limited, and any change in thickness does not affect the effect, as long as the epitaxial structure with a bias-voltage tunable spectral response curve does not affect the effect; the specific shape of the micro-nano optical structure is not limited, for example, it can be nano-cylinders with different diameters, or ellipsoidal cylinders with different major-axis orientations, etc., as long as the micro-nano optical structure sensitive to polarization does not affect the effect. The epitaxial structure layer of the active region on the substrate can be any one of GaN, AlN, InN, GaAs, AlAs, InAs, GaP, AlP, and InP. The epitaxial structure layer of the active region (from the first N-type semiconductor material layer 2 to the second N-type semiconductor material layer 6) is etched to form different micro-nano optical structures, so that the device generates an optical response with optical field polarization control.

[0051] By etching, a specific micro-nano optical structure is formed in the active region of the photodetector, or the electrode on the top of the device is replaced with a transparent electrode, and micro-nano optical structures with different polarization responses are integrated on the transparent electrode. This structure is anisotropic, so that the device generates different responses to different polarized lights. Finally, through a reconstruction algorithm, the reconstruction of spectral data and images can be achieved based on the spectral response curves under different bias voltages.

[0052] According to the embodiments of the present disclosure, as shown in combination with Figure 1 and Figure 2 shown, prepare as Figure 2When the optical field detector shown includes:

[0053] (1): Epitaxially grow thin film structures such as a first N-type semiconductor material layer 2, a first undoped semiconductor material layer 3, a P-type semiconductor material layer 4, a second undoped semiconductor material layer 5, and a second N-type semiconductor material layer 6 on a substrate 1. According to actual process requirements, each epitaxial layer structure can be prepared as a thin film, or can be in the form of nanocolumns or nanowires, etc.

[0054] (2): Etch the epitaxial wafer obtained in step (1) using photolithography and dry etching processes to expose the surface of the first N-type semiconductor material 2.

[0055] (3): Fabricate a first electrode 7 on the surface of the exposed first N-type semiconductor 2 of the product obtained in step (2) through photolithography, evaporation, and annealing processes. The first electrode 7 is a multi-metal such as Ti / Al / Ti / Au, Ti / Au, Ti / Al / Ni / Au, Cr / Au, or Cr / Al / Ti / Au.

[0056] (4): Fabricate a second electrode 8 on the surface of the exposed second N-type semiconductor of the product obtained in step (3) through photolithography, evaporation, and annealing processes. The second electrode 8 is a multi-metal such as Ti / Al / Ti / Au, Ti / Au, Ti / Al / Ni / Au, Cr / Au, or Cr / Al / Ti / Au.

[0057] According to an embodiment of the present disclosure, in combination with Figure 1 and as Figure 3 shown, fabricate Figure 3 the optical field detector shown, including:

[0058] (1): Epitaxially grow thin film structures such as a first N-type semiconductor material layer 2, a first undoped semiconductor material layer 3, a P-type semiconductor material layer 4, a second undoped semiconductor material layer 5, and a second N-type semiconductor material layer 6 on a substrate 1 and expose the surface of the first N-type semiconductor material 2. According to actual process requirements, each epitaxial layer structure can be prepared as a thin film, or can be in the form of nanocolumns or nanowires, etc. Each epitaxial layer in the active region on the substrate can be a thin film structure, or a nanocolumn structure, a nanowire structure, or other irregular structures.

[0059] (2): Fabricate a first electrode 7 on the surface of the exposed first N-type semiconductor 2 of the product obtained in step (1) through photolithography, evaporation, and annealing processes. The first electrode 7 is a multi-metal such as Ti / Al / Ti / Au, Ti / Au, Ti / Al / Ni / Au, Cr / Au, or Cr / Al / Ti / Au.

[0060] (3): On the article obtained in step (2), a second electrode 8 is fabricated on the exposed surface of the second N-type semiconductor through photolithography, evaporation, and annealing processes. The second electrode 8 is a multi-metal such as Ti / Al / Ti / Au, Ti / Au, Ti / Al / Ni / Au, Cr / Au, or Cr / Al / Ti / Au.

[0061] (4): The second electrode prepared in step (3) can also be a transparent electrode (such as ITO), so that a micro-nano optical structure can be further fabricated on the surface of the second electrode 8, enabling incident light to enter from the electrode side.

[0062] It should be noted that changes in the etched mesa size of the light field detector device, electrode pattern design, and epitaxial structure do not affect the technical effects.

[0063] According to an embodiment of the present disclosure, there is also provided a light field imager based on the above-described micro-nano optical structure-based micro light field detector array. The implementation manner of the light field detector array is that each light field detector unit is individually controlled by an external electrical circuit, or multiple light field detector units are controlled in a parallel, series, or series-parallel combination manner to achieve spectral detection, analysis, and spectral imaging for a spectrum within a certain wavelength range, including information on the linear polarization degree and circular polarization degree of light.

[0064] The light field detector and light field imager based on the micro-nano optical structure of the present disclosure have the following beneficial effects:

[0065] (1) Realization of the simplification of the miniaturized high-dimensional light field detector: Spectral and polarization reconstruction is achieved by relying on different light response behaviors to different wavelengths and polarizations under different voltage drives. Therefore, a single device can complete the functions of spectral and polarization reconstruction.

[0066] (2) High response efficiency: The different light response behaviors generated by this miniaturized high-dimensional light field detector are essentially formed by cascading two (forming a group) or more (forming multiple groups) detectors with different response ranges and opposite directions in the vertical direction. Its photocurrent all comes from its unintentionally doped active region. Therefore, the light response efficiency of the detector can be guaranteed at a relatively high level.

[0067] (3) Realization of the miniaturization of the miniaturized high-dimensional light field detector: The light field detector of the present disclosure does not require the integration of discrete optical elements. Instead, spectral and polarization simultaneous detection is achieved by forming a micro-nano optical structure in the active region on a single chip or integrating a micro-nano optical structure with different polarization responses on the electrode, greatly reducing the system volume. For example, a micro light field detector or spectrometer of any size from 1μm 2 - 1000mm 2 can be realized.

[0068] (4) Realized the array and large-scale production of miniaturized high-dimensional light field detectors: The light field detectors of the present disclosure are manufactured using standard III-V semiconductor processes, have the ability for large-scale production and integration, and a two-inch wafer-level product demonstration has been carried out.

[0069] (5) Realization of a miniaturized high-dimensional light field imager: The light field imager of the present disclosure is compatible with the manufacturing process of a focal plane array (FPA). Therefore, array-level high-dimensional light field detector products have been prepared, realizing a miniaturized integrated spectral imager.

[0070] (6) Realization of a full-spectrum miniaturized high-dimensional light field imager: The present disclosure only requires cascading light detectors with broad spectral responses, and the top is a structure formed by narrow spectral responses. Therefore, III-V semiconductor material systems (the response wavelength range corresponding to the bandgap width of this material system covers ultraviolet to infrared) can be used to realize the full spectrum from ultraviolet to infrared or the spectrum within any wavelength range from ultraviolet to infrared.

[0071] The light field detector and light field imager based on micro-nano optical structures of the present disclosure form a micro-nano optical structure sensitive to polarization through micro-nano processing of an epitaxial structure with bias-controlled spectral response to achieve polarization detection; or form a special micro-nano optical structure on the surface of a transparent electrode to achieve polarization detection. This structure can be nano-cylinders with different diameters, elliptical cylinders with different orientations, etc.; a miniaturized high-dimensional light field detector based on this epitaxial structure (combining a reconstruction algorithm to achieve spectral and polarization resolution); the realization of a high-dimensional light field imager based on an array of this miniaturized high-dimensional light field detectors; this high-dimensional light field imager can achieve a full-spectrum (10 nm to 10 μm) working range or a broad spectral range from deep ultraviolet to infrared within this wavelength range; among them, the epitaxial structure with bias-controlled spectral response can be a cascaded back-to-back diode, a compositionally graded PIN diode, etc., as long as it has a bias-controlled spectral response and a structure that can perform spectral reconstruction on this response through an algorithm; this high-dimensional light field imager does not depend on a specific material, and arsenides, III-V, II-VI groups can all achieve the realization of this structure.

[0072] So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that, in the accompanying drawings or the text of the specification, the implementation manners that are not illustrated or described are all forms known to those of ordinary skill in the art and have not been described in detail. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or manners mentioned in the embodiments, and those of ordinary skill in the art can make simple changes or replacements to them.

[0073] It should be noted that in this text, unless otherwise specified, an element with "a" does not necessarily mean only one such element, but may have one or more such elements.

[0074] In addition, in this text, unless otherwise specified, ordinal numbers such as "first", "second", etc. are only used to distinguish multiple elements with the same name, and do not indicate the existence of a rank, hierarchy, execution order, or process order between them. A "first" element and a "second" element may appear in the same component together, or in different components respectively. The existence of an element with a larger ordinal number does not necessarily mean the existence of another element with a smaller ordinal number.

[0075] In this text, unless otherwise specified, the so-called feature A "or" (or) or "and / or" feature B means that A exists alone, B exists alone, or A and B exist simultaneously; the so-called feature A "and" (and) or "and" (and) or "and" (and) feature B means that A and B exist simultaneously; the so-called "comprising", "including", "having", "containing" means including but not limited to this.

[0076] In addition, in this text, terms such as "above", "below", "left", "right", "front", "rear", or "between" are only used to describe the relative positions between multiple elements, and can be extended in interpretation to include cases of translation, rotation, or mirroring. In addition, in this text, unless otherwise specified, the statement that "one element is on another element" or a similar statement does not necessarily mean that the element contacts the other element.

[0077] In addition, unless specifically described or steps that must occur in sequence, the order of the above steps is not limited to those listed above, and can be changed or rearranged according to the required design. And the above embodiments can be used in combination with each other or combined with other embodiments based on considerations of design and reliability, that is, the technical features in different embodiments can be freely combined to form more embodiments.

[0078] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present disclosure. It should be understood that the above are only specific embodiments of the present disclosure and are not used to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. An optical field detector based on a micro-nano optical structure, comprising: Substrate, active region, electrode, and micro-nano optical structure; Among them, the micro-nano optical structure is fabricated on the surface of the active region and / or the electrode; the micro-nano optical structure fabricated on the active region is used to regulate the light field distribution of incident light in the active region, and the micro-nano optical structure fabricated on the electrode surface is used to regulate the transmittance of incident light, so that the light field detector generates different adjustable light responses to incident light carrying different optical information under the drive of different voltages, so as to realize the adjustable reconstruction of multi-dimensional optical information of the incident light; the optical information includes wavelength information, optical power information, light polarization information, and light phase information.

2. The light field detector according to claim 1, wherein, The active region generates a specific broad-spectrum response to light with an incident light wavelength falling within the range of 10 nm to 10 μm; when the micro-nano optical structure is fabricated on the active region, the incident light can enter from the substrate or electrode side; when the micro-nano optical structure is fabricated on the electrode surface, the electrode is a transparent electrode, so that the incident light can enter from the electrode side.

3. The light field detector according to claim 1, wherein the optical information further includes spin information or mode information.

4. The optical field detector according to claim 1, wherein the micro-nano optical structure is an anisotropic nano-column array, and the shape of the horizontal cross-section of the nano-column includes an ellipse, a circle, a polygon or an irregular shape; the nano-column array includes nano-columns with multiple different cross-sectional areas, and / or nano-columns with multiple different spacings, and / or nano-columns with multiple different cross-sectional shapes; the horizontal cross-sectional area of each nano-column is 1 nm 2 - 1000 um 2 , the spacing between the nano-columns is 1 nm - 1000 um, the height of the nano-columns is 1 nm - 1000 um, and the array forms formed by the nano-columns include a photonic crystal structure, a metasurface structure and a surface plasmon structure.

5. The optical field detector according to claim 1, wherein the micro-nano optical structure is a nano-pore array with anisotropy, and the cross-section of the nano-pores includes an ellipse, a circle, a polygon, and / or an irregular shape; the nano-pore array includes a plurality of nano-pores with different cross-sectional areas, and / or a plurality of nano-pores with different spacings, and / or a plurality of nano-pores with different cross-sectional shapes; the area of each nano-pore is 1 nm 2 -1000 um 2 , the spacing between the nano-pores is 1 nm - 1000 um, the depth of the nano-pores is 1 nm - 1000 um, and the array forms formed by the nano-pores include a photonic crystal structure, a metasurface structure, and a surface plasmon structure.

6. The optical field detector according to claim 1, wherein the micro-nano optical structure is an anisotropic annular column array, and the cross-sectional shape of the annular column includes a circular ring, an elliptical ring, a polygonal ring, and / or an irregular ring shape; the annular column array includes a plurality of annular columns with different cross-sectional areas, and / or a plurality of annular columns with different spacings, and / or a plurality of annular columns with different cross-sectional shapes, and the area of each nano-ring is 1 nm 2 -1000 um 2 , the spacing between nano-pores is 1 nm - 1000 um, the height of the nano-ring is 1 nm - 1000 um, and the array forms formed by the annular nano-columns include a photonic crystal structure, a metasurface structure, and a surface plasmon structure.

7. The optical field detector according to claim 1, wherein the micro-nano optical structure is a grating array with anisotropy. The grating array includes a plurality of array units with different cross-sectional areas, and / or a plurality of array units with different spacings, and / or a plurality of array units with different orientations. The cross-sectional area of each array unit is 1 nm 2 - 1000 um 2 , the spacing between the array units is 1 nm - 1000 um, and the unit height is 1 nm - 1000 um.

8. The light field detector according to claim 1, wherein the active region is configured as a light-detecting semiconductor epitaxial structure having a broad-spectrum response and an adjustable light response curve with the change of an external bias voltage.

9. The light field detector according to claim 8, wherein the active region includes, from bottom to top, a first N-type semiconductor material layer, a first unintentionally doped semiconductor material layer, a P-type semiconductor material layer, a second unintentionally doped semiconductor material layer, and a second N-type semiconductor material layer.

10. A light field imager based on the light field detector array according to any one of claims 1-9, wherein the light field detector array is realized by individually controlling each light field detector unit through an external electrical circuit, or by controlling multiple light field detector units in parallel, in series, or in a combination of series and parallel, so as to perform spectral detection, analysis, and spectral imaging on the spectrum within a certain wavelength range, including the linear polarization degree and circular polarization degree information of light.

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