On-chip spectrometer and spectral imager based on vertical integration technology of transparent substrate

Abstract

The invention provides an on-chip spectrometer based on a vertical integration technology of a transparent substrate and a spectral imager. The on-chip spectrometer comprises the transparent substrate; the at least one on-chip optical filter is prepared on the surface of one side of the transparent substrate, and each on-chip optical filter is configured to be used for carrying out targeted filtering shaping on incident light; and the at least one on-chip light detector is prepared on the surface of the other side of the transparent substrate, and each on-chip light detector is configured to perform targeted detection on the incident light after filtering and shaping so as to generate different photoelectric response results and realize high-precision spectral analysis and spectral imaging.

Description

Technical Field

[0001] The present disclosure relates to the fields of optoelectronics and semiconductor technologies, and particularly to an on-chip spectrometer and spectral imager based on a vertical integration technology with a transparent substrate. Background Art

[0002] Spectrometers are key instruments required in various academic and industrial applications such as biomedical, chemical, and environmental engineering. The miniaturization feature of micro-spectrometers provides superior portability, flexibility, and cost-effectiveness. It can provide detailed information on various spectral components of incident light, and these spectral information reveal rich information about the composition and structure of various observed substances. This ability to reveal fine information is usually attributed to its resolution. Therefore, in recent years, researchers have been committed to improving the resolution of spectrometers.

[0003] Existing coded spectrometers adopt a fixed-pixel filtering mode, which requires sacrificing spatial or spectral dimension information. Although liquid crystal tunable filtering technology realizes dynamic coding through electronic tuning, its response speed is slow (millisecond level) and it cannot be miniaturized. Current micro-spectral technologies mainly rely on planar integrated filter or grating spectroscopic systems, such as a multi-layer silicon-based filter-detector stacking scheme, which realizes multi-spectral detection through the combination of discrete band-pass filter layers and the detector plane. However, limited by the number of layers (usually <10 layers) and optical accumulation loss, it is difficult for the spectral resolution to break through 5nm.

[0004] In view of the above limitations, it is necessary to design a new integrated technology solution to make full use of the chip space and realize a miniaturized and high-precision spectrometer. Summary of the Invention

[0005] 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 on-chip spectrometer and spectral imager based on a vertical integration technology with a transparent substrate.

[0006] To achieve the above object, the technical solution of the present disclosure is as follows:

[0007] According to an embodiment of one aspect of the present disclosure, there is provided an on-chip spectrometer based on a vertical integration technology with a transparent substrate, including: a transparent substrate; at least one on-chip filter, prepared on the surface of one side of the transparent substrate, each on-chip filter being configured to perform targeted filtering and shaping on incident light; and at least one on-chip photodetector, prepared on the surface of the other side of the transparent substrate, each on-chip photodetector being configured to be able to perform targeted detection on the filtered and shaped incident light to generate different optoelectronic response results.

[0008] According to an embodiment of the present disclosure, the on-chip filter includes a single-layer or multi-layer filter film structure.

[0009] According to an embodiment of the present disclosure, the filter thin film structure is selected from a metasurface structure, a photonic crystal structure, a grating structure, a plasmonic structure, a Fabry - Perot resonator structure, a quantum dot structure, or a filter film structure.

[0010] According to an embodiment of the present disclosure, the on - chip filter has nonlinear optical properties, and / or has electro - induced, temperature - induced, and mechanical stress - induced optical reflection, absorption, and transmission property changes, and / or has specific scattering for incident light.

[0011] According to an embodiment of the present disclosure, the on - chip filter is selected from low - dimensional materials and / or layered materials.

[0012] According to an embodiment of the present disclosure, each of the on - chip photodetectors performs targeted detection and monitoring on the spectra of different incident lights that have been filtered and shaped by the filter.

[0013] According to an embodiment of the present disclosure, the on - chip photodetector includes at least one photodetector epitaxial structure in the epitaxial direction; when multiple photodetector epitaxial structures are included, the multiple photodetectors will have different spectral responses to different spectral ranges of incident light, achieving different spectral responses to the spectra of incident light with wavelengths falling within the range of 10 nm to 10 μm.

[0014] According to an embodiment of the present disclosure, each on - chip photodetector includes an N - P - N photodetector epitaxial structure or multiple cascaded N - P - N photodetector epitaxial structures in the epitaxial direction.

[0015] According to an embodiment of the present disclosure, the material for preparing the transparent substrate is selected from semiconductors such as sapphire, silicon, germanium, silicon carbide, gallium oxide, boron nitride, diamond, aluminum nitride, gallium nitride, gallium arsenide, indium phosphide, or quartz glass or a substrate material that is transparent to light within the spectral range from deep ultraviolet light to infrared light; the material for preparing the on - chip photodetector is selected from binary, ternary, or quaternary metal nitrides of Ga, Al, In, or binary, ternary, or quaternary metal phosphides of Ga, Al, In, or binary, ternary, or quaternary metal arsenides of Ga, Al, In, or binary, ternary, or quaternary metal antimonides of Ga, Al, In.

[0016] An embodiment of another aspect of the present disclosure provides a spectral imager based on the on - chip spectrometer array described in any one of the above. The control mode of the spectrometer array is that each spectrometer unit is controlled by an independent circuit, or multiple spectrometer units are controlled in a parallel, series, or series - parallel combination manner to achieve high - precision spectral analysis and spectral imaging for spectra within a certain wavelength range. Description of the Drawings

[0017] Through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, the above and other objects, features, and advantages of the present disclosure will become clearer. In the drawings:

[0018] Figure 1 It is a schematic diagram of the generation principle of the filter channel in the on-chip spectrometer based on the vertical integration technology with a transparent substrate according to the embodiment of the present disclosure.

[0019] Figure 2 It is a schematic diagram of the structure of the on-chip spectrometer based on the vertical integration technology with a transparent substrate according to the embodiment of the present disclosure.

[0020] Figure 3 It is a schematic diagram of the working principle of the on-chip spectrometer based on the vertical integration technology with a transparent substrate according to the embodiment of the present disclosure.

[0021] Figure 4 It is a schematic diagram of the structure of the on-chip photodetector according to the embodiment of the present disclosure.

[0022] Figure 5 It is a schematic diagram of the structure of the on-chip photodetector array according to the embodiment of the present disclosure. Detailed implementation manners

[0023] The present disclosure provides an ultra-high-precision (capable of achieving picometer-level spectral resolution) monolithic integrated spectrometer and spectral imager based on vertical integration technology. The on-chip spectrometer is a spectrometer with ultra-high spectral resolution formed by a filter array and a photodetector array through vertical integration technology. The filter array and the photodetector array are integrated on both sides of a transparent substrate in a vertical integration manner to achieve the integration of spectral shaping coding and detection.

[0024] For a traditional Fourier transform spectrometer, its working principle is as follows: The light emitted by the light source is split into two beams by a beam splitter. One beam passes through the beam splitter and reaches the moving mirror, and the other beam is reflected by the beam splitter and reaches the fixed mirror. The two beams of light are reflected back to the beam splitter by the fixed mirror and the moving mirror respectively. The moving mirror moves in a straight line at a constant speed, so the two beams of light split by the beam splitter form an optical path difference and generate interference. The interfering light converges at the beam splitter and then passes through the sample cell. After passing through the sample, the interfering light containing sample information reaches the detector, and then the signal is processed by Fourier transform, and finally an absorption spectrum diagram showing the change of transmittance or absorbance with wavelength is obtained. The disadvantages include: a) High requirement for mechanical stability: During the generation of the optical path difference, the vibration of the moving mirror during movement will generate phase noise, resulting in a decrease in spectral accuracy; b) Limited resolution: The highest resolution is limited by the maximum optical path difference (Δλ = 1 / (2L), L > 2 cm to achieve 0.1 nm resolution); c) Difficulty in miniaturization: Restricted by various mechanical devices.

[0025] Principle of traditional planar integrated filter spectrometers: Planar filter spectrometers use spatial spectroscopy: light in different wavelength ranges is selectively transmitted by filters at corresponding positions, forming discrete channel responses. Disadvantages include: a) The stacking method of discrete components: The physical layer thickness stacking results in an overly large total device size, making it difficult to miniaturize; b) Sparse spectral channels due to a limited number of filter layers: It cannot meet the requirements of the Shannon sampling theorem for high resolution (typical value > 5 nm); c) Difficulty in improving the signal-to-noise ratio: The optical signal accumulatively attenuates due to reflection and absorption during layer-by-layer transmission (total loss > 60%); d) Although some dynamic filtering technologies introduce electronic control modulation, external drive circuits are required, sacrificing integration.

[0026] In response to the above problems, the monolithic integrated spectrometers and spectral imagers of the present disclosure propose a vertical integration scheme. As shown in combination with Figure 1 , Figure 2 and Figure 3 , by fabricating on-chip filters or filter arrays and on-chip photodetector arrays on both sides of a transparent substrate, the integration of spectral shaping encoding and detection is achieved. High-efficiency spectral shaping encoding is realized using densely encoded channels, and combined with spectral reconstruction algorithms, ultra-high-precision spectral measurement is achieved. During spectral reconstruction, for example, 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, which is processed by a large number of neurons, and its non-linear characteristics are captured through activation functions. 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 information. For example, the entire model can be trained in batches on a GPU with an initial learning rate of , 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 I-V curve and the spectrum, achieving high-precision spectral reconstruction. Thus, based on the spectral response curves under different bias voltages, the reconstruction of spectral data and images can be realized.

[0027] Working principle of the multi-channel filter array: Each independent channel filter has a characteristic wavelength selectivity for transmitting or reflecting the incident spectrum. Therefore, the intensities of certain wavelengths in the output spectrum are changed, and thus the spectral waveform is adjusted, that is, the spectrum is shaped and encoded. By designing different filter films, different spectral encoding effects can be achieved.

[0028] Principle of Distributed Bragg Reflector (DBR): First, the enhanced reflection principle of the Bragg reflector utilizes the interference between different light beams with a constant phase difference and the same direction to form enhanced reflection of light at a specific wavelength, achieving the effect of spectral shaping. Second, through special design of the mask for depositing the reflective film, 2 n encoding channels (n is the number of reflective film layers) are generated, greatly improving the spectral shaping efficiency and further enhancing the spectral measurement accuracy. In this disclosure, DBR is used as a filter. According to its principle, it has advantages such as continuously adjustable reflection center wavelength, simple preparation process, and strong process compatibility.

[0029] Vertical integration technology: The photodetector substrate used in this disclosure is a transparent substrate, which has the characteristic of high transparency. Utilizing this characteristic, a filter array is prepared on the back of the photodetector array to achieve vertical three-dimensional integration of the spectral shaping encoding filter and the photodetector, forming a miniaturized and high-precision spectrometer.

[0030] To make the purpose, technical solution, and advantages of this disclosure clearer and more understandable, the following further elaborates on this disclosure in detail with reference to specific embodiments and the accompanying drawings.

[0031] In an embodiment of this disclosure, a chip-based spectrometer based on vertical integration technology with a transparent substrate is provided. As Figure 2 shown, the chip-based spectrometer includes:

[0032] A transparent substrate;

[0033] At least one on-chip filter, prepared on the surface of one side of the transparent substrate, and each on-chip filter is configured to perform targeted filtering and shaping on incident light; and

[0034] At least one on-chip photodetector, prepared on the surface of the other side of the transparent substrate, and each on-chip photodetector is configured to be able to perform targeted detection on the filtered and shaped incident light to generate different optoelectronic response results.

[0035] According to an embodiment of this disclosure, the preparation material of the on-chip filter is selected from materials that are transparent to incident light. For example, the on-chip filter includes a single-layer or multi-layer filter thin film structure; the filter thin film structure is selected from a metasurface structure, a photonic crystal structure, a grating structure, a plasma structure, a Fabry-Perot resonator structure, a quantum dot structure, or a filter sheet structure. The on-chip filter has nonlinear optical characteristics, and / or has optical reflection, absorption, and transmission characteristic changes caused by electricity, temperature, and mechanical stress, and / or has specific scattering for incident light. The on-chip filter can be selected from low-dimensional materials and / or layered materials.

[0036] According to embodiments of the present disclosure, each of the on-chip filters is configured to perform targeted filtering and shaping on incident light. For example, the on-chip spectrometer includes a plurality of different on-chip filters. The first on-chip filter can filter and shape incident light of a certain wavelength or a certain wavelength range in the incident light of 10 nm - 10 μm. The detector corresponding to (e.g., position-corresponding or function-corresponding) this on-chip filter then detects light of a certain wavelength or a certain wavelength range after the action of this on-chip filter to generate different optoelectronic response results. It should be noted that the on-chip filter array can be correspondingly configured according to the actual range of the working wavelength or the detection spectrum, and the on-chip photodetector can also be set and selected according to the working wavelength.

[0037] According to embodiments of the present disclosure, the on-chip photodetector includes at least one photodetector epitaxial structure in the epitaxial direction; when including a plurality of photodetector epitaxial structures, the plurality of photodetectors will generate different spectral responses to different spectral ranges of incident light, realizing different spectral responses to the spectrum with the incident light wavelength falling within the range of 10 nm to 10 μm. It should also be noted that the on-chip photodetector can be a single photodetector or an array of photodetectors formed by connecting multiple photodetectors in series and / or in parallel. The on-chip photodetector and the on-chip filter can be in a thin film structure, a nanowire structure, a nanorod structure, or other irregular structures.

[0038] According to embodiments of the present disclosure, the preparation material of the transparent substrate is selected from semiconductors such as sapphire, silicon, germanium, silicon carbide, gallium oxide, boron nitride, diamond, aluminum nitride, gallium nitride, gallium arsenide, and indium phosphide, or substrate materials that are transparent to light in the spectral range from deep ultraviolet light to infrared light, and it only needs to be transparent within the working wavelength range of the detector, and can be selected according to the type of detector; the preparation material of the on-chip photodetector is selected from binary, ternary, or quaternary metal nitrides of Ga, Al, In, or binary, ternary, or quaternary metal phosphides of Ga, Al, In, or binary, ternary, or quaternary metal arsenides of Ga, Al, In, or binary, ternary, or quaternary metal antimonides of Ga, Al, In. Each layer of material in the epitaxial structure of the on-chip photodetector is selected from the corresponding materials with fixed composition, or materials with gradually changing composition, or materials with stepwise changes or non-linear increase and decrease changes among the above materials. The thickness of each layer in the epitaxial structure of the on-chip spectrometer is between 0.1 nm and 5 μm. Any change in thickness can achieve the corresponding effect. Changing the composition distribution form of each layer of material can change the light absorption performance. For example, a layer with gradually changing composition can achieve light absorption in a wide spectral range. Specifically, during the epitaxial growth of the material, along the epitaxial direction, by gradually changing the composition of the material, materials with different compositions correspond to absorbing the wavelength range corresponding to the material, generating a certain amount of photo-generated electrons and hole pairs, and finally realizing a photocurrent response curve for a specific spectrum, providing a device basis for subsequent spectrum reconstruction.

[0039] According to embodiments of the present disclosure, each on-chip filter can include multiple layers of filter films, and each layer of filter film includes multiple different filter windows. By superimposing the filter windows at different positions between the multiple layers of filter films, different filter channels can be formed, thereby expanding the number of spectrally shaped and encoded filter channels.

[0040] According to embodiments of the present disclosure, the on-chip photodetector can be a bias-adjustable light response type photodetector, which can further improve the spectrum reconstruction ability.

[0041] According to embodiments of the present disclosure, each on-chip photodetector includes an N-P-N photodetector epitaxial structure or multiple cascaded N-P-N photodetector epitaxial structures in the epitaxial direction. Each on-chip photodetector can also include at least two cascaded bottom diode structures and top diode structures in the epitaxial direction, that is, a group of cascaded diode epitaxial structures.

[0042] According to embodiments of the present disclosure, each on-chip photodetector can include multiple semiconductor photodetector epitaxial structures, such as Figure 4As shown, the on-chip photodetector includes three different semiconductor photodetector epitaxial structures: the first photodetector epitaxial structure, the second photodetector epitaxial structure, and the third photodetector epitaxial structure. The first photodetector epitaxial structure has a first spectral response to the spectrum, the second photodetector epitaxial structure has a second spectral response to the spectrum, and the third photodetector epitaxial structure has a third spectral response to the spectrum. The number of semiconductor photodetector epitaxial structures can be adjusted according to actual application scenarios; for example, the semiconductor photodetector epitaxial structure can also be at least two cascaded photodiode epitaxial structures for different light response ranges along the material epitaxial direction. For example, based on the n-i-p type diode with a wide spectral response at the bottom and the p-i-n type diode with a narrow spectral response at the top of the cascaded photodiode 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 voltage conditions, the energy band offset trends of the two diodes will change, thereby changing the intensity and characteristics of the photocurrent competition and resulting in an adjustable spectral response curve. Therefore, through the deep neural network calculation and reconstruction algorithm, the spectral response curves obtained based on different bias voltages are trained. Based on this, when an unknown light beam is incident, the obtained spectral response curves based on different bias voltages can be used to compare and reconstruct with the curves obtained through training, thereby finally realizing spectral data reconstruction. Furthermore, we fabricate a single spectrometer (i.e., a single-pixel image formed by a single device) into an array and connect them in series and parallel to achieve the function of single-shot high-resolution spectral imaging. The realization of this function lays the 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 current-voltage (I-V) curve data, 1. First, the device response obtained through I-V measurement is used as the input signal, which is processed by a large number of neurons and captures its non-linear characteristics through the activation function. 2. The residual block containing three fully connected layers is used to effectively prevent the vanishing gradient, thereby extracting 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 , and the 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 I-V curve and the spectrum, and achieve high-precision spectral reconstruction. Thus, based on the spectral response curves under different bias voltages, the reconstruction of spectral data and images can be realized.

[0043] Each on-chip photodetector may include, for example, two cascaded bottom diode structures and a top diode structure, i.e., a group of cascaded diode epitaxial structures. For example, the bottom one is an n-i-p type diode, and the upper one is a p-i-n type diode, and stacking can continue. 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. Among them, i (intrinsic) in the n-i-p or p-i-n layer represents an intrinsic epitaxial layer, and n and p represent an n-type semiconductor material layer and a p-type semiconductor material layer respectively. The material in the intrinsic epitaxial layer can be a material with a fixed composition, a material with a gradually changing composition, or a material with a stepwise change. The way of composition change can be a gradual increase; a gradual decrease; first increase and then decrease; first decrease and then increase; or non-linear increase and decrease, etc. In this optoelectronic cascaded diode, except for the intrinsic layer, the composition of each other epitaxial layer can be fixed or a material with a changing composition, such as a material with a gradually changing composition. Among them, the thickness of each gradient layer ranges from 0.1 nm to 5 μm. The way of composition gradient (how fast the composition changes with thickness) only changes the specific photocurrent response performance, spectral resolution ability and accuracy of the cascaded photodiode, but can all meet the requirements for realizing a micro spectrometer (that is, the response of the cascaded photodiode to light of a specific wavelength changes with the bias voltage). In addition, different light responses can also be realized under different bias voltages based on an n-i-p type diode or a p-i-n type diode, so as to construct 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 of this cascaded diode or the connection between any two layers. 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 around the insertion position, but the proportion of the material components is different from that of the surrounding. In addition, it should be noted that the intrinsic epitaxial layer in the cascaded photodiode epitaxial structure can also be doped with n-type or p-type, and the doping concentration ranges from the completely undoped case to the electron concentration in n-type doping or the hole concentration in p-type doped GaN layer.It should be noted that due to the mutual cascading of two or several photodiodes, there is always one or several photodiodes operating in either the forward or reverse bias state regardless of whether it is a positive or negative voltage. That is, at least one photodiode in this cascaded photodiode operates in the forward bias state and at least one photodiode operates in the reverse bias state. As a result, the leakage current of the photonic cascaded diode is extremely low, which has significant advantages in terms of device stability and energy consumption, and is also beneficial to improving the spectral measurement and spectral resolution capabilities (resolution) of the spectrometer.

[0044] The present disclosure also provides a spectral imager for an on-chip spectrometer array based on the above-mentioned vertical integration technology based on a transparent substrate. The control mode of the spectrometer array is that each spectrometer unit is controlled by an independent circuit, or multiple spectrometer units are controlled in a parallel, series, or series-parallel combination manner to achieve high-precision spectral analysis and spectral imaging of the spectrum within a certain wavelength range. For example, spectral analysis and spectral imaging are performed on the spectrum within any wavelength range where the incident light wavelength falls within the range of 10 nm to 10 μm.

[0045] According to an embodiment of the present disclosure, the on-chip photodetector in each on-chip spectrometer can be a single photodetector, or multiple identical or different photodetectors can be connected in series and / or in parallel to form a photodetector array, as Figure 5 shown, including a total of six different detectors, namely on-chip detector 10 to on-chip detector 60. When it is a photodetector array, each type of detector can mainly effectively detect the spectrum within a specific wavelength band range. By connecting multiple different detectors in series or in parallel, an array can be formed, that is, an overall "detector". Different types of detectors can be realized by selective area epitaxial growth, or by physical transfer, or by bonding, or by mechanical exfoliation, or by using low-dimensional materials through van der Waals contact.

[0046] In the prior art, there are solutions for "package integration" or "chip mounting integration" of similar filter structures with traditional CCD imaging chips, imaging arrays, or imaging units. However, the semiconductor micro-spectrometer technology of this application integrates a filter array directly on the imaging chip, that is, it adopts the "monolithic integration technology", and the technical routes are different. To achieve the monolithic integration technology, a transparent substrate must be used, such as a sapphire substrate, a glass substrate, or other transparent substrates. Using the transparent substrate, the filter array composed of filters and the detector array fabricated on the substrate are integrated on the chip. The detector array is fabricated on the front side of the substrate, and the filter module array is fabricated on the back side of the substrate. A transparent substrate is sandwiched between a single filter or filter array and a single detector or detector array. During the arrangement process of each filter or filter array, their positions should correspond to each detector or an array composed of multiple same detectors or an array composed of multiple different detectors fabricated on the other side of the transparent substrate. In addition, a single filter can correspond to a single detector or a detector array, and a filter array can correspond to only one detector or a detector array.

[0047] Taking the on-chip filter including multiple filter thin films as an example to illustrate the preparation of the on-chip spectrometer, the preparation method of the on-chip spectrometer based on the vertical integration technology of a transparent substrate according to the present disclosure includes

[0048] Step 1: Fabricate an on-chip photodetector array on the transparent substrate;

[0049] As long as the on-chip photodetector array has different characteristic responses to spectra of different shapes.

[0050] Step 2: Generate a first deposition pattern window on the back side of the transparent substrate through a photolithography process;

[0051] Step 3: Deposit a first filter thin film by a magnetron sputtering method;

[0052] Step 4: Remove the photoresist;

[0053] Step 5: Generate a deposition window staggered with the first filter thin film on the first filter thin film through a photolithography process;

[0054] Step 6: Deposit a second filter thin film by a magnetron sputtering method;

[0055] And so on. As Figure 1 shown, 4 filter thin films can be fabricated. As Figure 2 shown, each on-chip filter can be fabricated with different numbers of filter thin films. For example, some are six layers, some are two layers, or three layers, etc. Figure 1 The combination method of the number of channels is also shown. The number of filter channels N generated by this method is 2 n, where n is the number of layers of the filter film, and efficient spectral shaping and encoding filter channels can be generated.

[0056] Similarly, the generation of efficient spectral shaping channels realized by the above filter array based on the multi-layer filter film structure can also be achieved by integrating a metasurface optical film on the back of the transparent substrate, such as metasurface structures (preparing sub-wavelength grating arrays through electron beam lithography and high refractive index materials (such as silicon nitride, titanium nitride), and realizing nano-scale wavelength selective reflection through periodic interference regulation), anisotropic structures (such as gradient nanowires, realizing spectral polarization-sensitive filtering), multi-layer heterogeneous metasurface stacks (such as Si / ITO / TiO2, regulating light in corresponding bands in different layers and coupling optical signals through vertical waveguides, greatly improving the spectral channel density), etc. It breaks through the resolution and integration bottlenecks of traditional planar filters with low-cost semiconductor processes, and opens up a new path for the miniaturization and high-precision of spectrometers.

[0057] So far, the vertically integrated ultra-high-precision spectrometer of the present disclosure has been described in detail. By fabricating a multi-channel filter on the back of the transparent substrate of the photodetector to encode and shape the incident spectrum, and finally reconstructing the spectral information through an algorithm, an ultra-high-precision spectrometer is realized.

[0058] The on-chip spectrometer based on the vertical integration technology of the transparent substrate of the present disclosure has the following technical effects:

[0059] 1. Integration of spectral encoding and measurement function modules: The filter array and the photodetector array are fabricated on both sides of the sapphire substrate through vertical integration, realizing the miniaturization of the spectrometer system. Within the range allowed by semiconductor processes, a micro spectrometer with any size from 1 nm 2 - 1000 mm 2 can be realized, and a nano-scale micro spectrometer can be achieved.

[0060] 2. Efficient spectral shaping and encoding: An exponential number of encoding channels are realized through a tunable filter array (DBR filter array), greatly improving the spectral shaping and encoding efficiency, and thus improving the spectral measurement accuracy.

[0061] 3. Continuously tunable spectral encoding: Due to the flexible design characteristics of the DBR filter, continuously tunable spectral shaping and encoding over a wide spectrum are realized.

[0062] 4. Ultra-high-precision spectral measurement: Due to the generation of an efficient number of spectral shaping channels, spectral accuracy measurement at the picometer level is realized.

[0063] Based on the above vertically integrated ultra-high-precision spectrometer structure and its manufacturing method, a wide-spectrum, ultra-high-precision spectrometer can be realized by adjusting the characteristic response band of the photodetector and the working spectral range of the filter.

[0064] The above-described content only presents one or more implementation schemes for implementing the present disclosure. However, the detector array, filter array, and process conditions in this scheme can be modified or equivalently replaced. Such changes do not depart from the idea and scope of the present disclosure and should all be covered within the protection scope.

[0065] So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that the implementation manners not illustrated or described in the accompanying drawings or the text of the specification 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 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.

[0066] In addition, in this article, 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, level, 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.

[0067] In this article, unless otherwise specified, the so-called feature A "or" (or) or "and / 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.

[0068] In addition, in this article, terms such as "upper", "lower", "left", "right", "front", "rear", or "between" are only used to describe the relative positions between multiple elements and can be extended in the interpretation to include translation, rotation, or mirroring situations. In addition, in this article, 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.

[0069] In addition, unless otherwise specially described or steps that must occur in sequence, the order of the above steps is not limited to the above list and can be changed or rearranged according to the required design. And the above embodiments can be mixed and used with each other or mixed and used with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.

[0070] 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 on-chip spectrometer based on a vertical integration technology with a transparent substrate, comprising: A transparent substrate; At least one on-chip filter, prepared on the surface of one side of the transparent substrate, each on-chip filter being configured to perform targeted filtering and shaping on incident light; And At least one on-chip photodetector, prepared on the surface of the other side of the transparent substrate, each on-chip photodetector being configured to be able to perform targeted detection on the filtered and shaped incident light to generate different optoelectronic response results, realizing high-precision spectral analysis and spectral imaging.

2. The on-chip spectrometer according to claim 1, wherein the on-chip filter comprises a single-layer or multi-layer filter film structure.

3. The on-chip spectrometer according to claim 2, wherein the filter film structure is selected from a metasurface structure, a photonic crystal structure, a grating structure, a plasmonic structure, a Fabry-Pérot resonator structure, a quantum dot structure, or a filter sheet structure.

4. The on-chip spectrometer according to claim 1, wherein the on-chip filter has nonlinear optical properties, and / or has electro-optic, thermo-optic, and mechanical stress-induced optical reflection, absorption, and transmission property changes, and / or has specific scattering of incident light.

5. The on-chip spectrometer according to claim 1, wherein the on-chip filter is selected from low-dimensional materials and / or layered materials.

6. The on-chip spectrometer according to claim 1, wherein each on-chip photodetector performs targeted detection and monitoring on the spectra of different incident lights filtered and shaped by the filter.

7. The on-chip spectrometer according to claim 1, wherein the on-chip photodetector at least comprises one photodetector epitaxial structure in the epitaxial direction; when multiple photodetector epitaxial structures are included, the multiple photodetectors will generate different spectral responses to the spectral ranges of different incident lights, realizing different spectral responses to the spectra of incident lights with wavelengths falling within the range of 10 nm to 10 μm.

8. The on-chip spectrometer according to claim 1, wherein each on-chip photodetector comprises an N-P-N photodetector epitaxial structure or multiple cascaded N-P-N photodetector epitaxial structures in the epitaxial direction.

9. The on-chip spectrometer according to claim 1, wherein: The material for preparing the transparent substrate is selected from semiconductors such as sapphire, silicon, germanium, silicon carbide, gallium oxide, boron nitride, diamond, aluminum nitride, gallium nitride, gallium arsenide, and indium phosphide, or quartz glass, or a material having transparency to light within the spectral range from deep ultraviolet light to infrared light; The material for preparing the on-chip photodetector is selected from binary, ternary, or quaternary metal nitrides of Ga, Al, and In, or binary, ternary, or quaternary metal phosphides of Ga, Al, and In, or binary, ternary, or quaternary metal arsenides of Ga, Al, and In, or binary, ternary, or quaternary metal antimonides of Ga, Al, and In.

10. A spectral imager based on the on-chip spectrometer array according to any one of claims 1-9, wherein the control mode of the spectrometer array is that each spectrometer unit is controlled by an independent circuit, or multiple spectrometer units are controlled in a parallel, series, or series-parallel combination manner to achieve high-precision spectral analysis and spectral imaging for spectra within a certain wavelength range.

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