Miniature spectrometer and manufacturing method thereof

Abstract

The invention relates to the field of spectrum processing, and provides a micro spectrometer and a manufacturing method thereof, the micro spectrometer comprises a metasurface, the metasurface comprises a thin film with a plurality of grating structures, the plurality of grating structures are configured to generate qBIC modes for light with different wavelengths and output corresponding light intensities, the energy band of the grating structure presents flat-band dispersion in an incidence angle range of-10 degrees to + 10 degrees; the photoelectric detector is used for detecting the light intensity output by the plurality of grating structures of the metasurface and outputting an electric signal; and the calculation module is used for decoding the electric signal to obtain spectral information. According to the invention, the photon quasi-bound state (qBIC) and photon flat band characteristics in the continuous medium are utilized to realize high-sensitivity, high-performance and angle-insensitive spectrum detection.

Description

Technical Field

[0001] The present application relates to the field of spectrum processing technology, and in particular to a miniature spectrometer and a manufacturing method thereof. Background Art

[0002] A core issue in the design of optical sensing devices is how to use photons most efficiently and, in the process, extract as much information as possible from the incident radiation, i.e., the efficiency or sensitivity of the system, which determines the ability of the optical sensing device to collect data with a satisfactory resolution within a given time frame. However, under uncontrolled or low-intensity ambient lighting, for platforms based on traditional strategies (e.g., those using grating dispersion or filter arrays), higher resolution usually has to come at the expense of the intensity of the transmitted light incident on the detector, resulting in reduced signal-to-noise ratios (SNRs) and longer integration times. Therefore, when the size of the device and detector is reduced, a major limitation of the design of optical sensing devices lies in the inherent trade-off between resolution and sensitivity of miniaturized devices. The usual choice of optical sensing devices in related technologies is to use high-sensitivity detectors that can be cooled, but this is an impractical solution for many in situ or portable devices. Summary of the Invention

[0003] In view of the above problems, the present application provides a micro-spectrometer that utilizes the quasi-bound states of photons in continuous media (qBIC) and the flat band characteristics of photons to achieve high-sensitivity, high-performance and angle-insensitive spectral detection.

[0004] An embodiment of the present application provides a miniature spectrometer, comprising:

[0005] A metasurface comprising a thin film having a plurality of grating structures, wherein the plurality of grating structures are configured to generate qBIC modes for light of different wavelengths and output corresponding light intensities, wherein the energy band of the grating structure exhibits flat-band dispersion within an incident angle range of -10 degrees to +10 degrees;

[0006] a photodetector, configured to detect the light intensity output by the plurality of grating structures of the metasurface and output an electrical signal;

[0007] A calculation module is used to decode the electrical signal to obtain spectral information.

[0008] In this embodiment, the qBIC mode of the metasurface generates flat-band dispersion, enabling high-sensitivity, wide-angle (-10° to +10°) spectral detection, making the micro-spectrometer insensitive to incident angle. The photodetector and computing module work together to convert the optical signal into an analyzable electrical signal, ultimately outputting precise spectral information. This design significantly reduces the size of traditional spectrometers while maintaining excellent spectral resolution capabilities.

[0009] In some possible implementations, the refractive index of the film is greater than or equal to 2.0 and less than or equal to 4.0; the grating structure includes a plurality of first grating units and a plurality of second grating units arranged along a first direction, the second grating units are located between two adjacent first grating units, the plurality of first grating units are arranged parallel to each other, and the plurality of second grating units are arranged parallel to each other; wherein,

[0010] The second grating units are arranged in parallel with the first grating units, and the first grating units and the second grating units have different widths;

[0011] The second grating units are arranged in parallel with the first grating units, and the first grating units and the second grating units are staggered in a second direction perpendicular to the first direction; or

[0012] The first grating unit forms a first angle with the first direction, and the second grating unit forms a second angle with the first direction, and the first angle is different from the second angle.

[0013] In some possible implementations, the refractive index of the film is greater than or equal to 2.0 and less than or equal to 4.0; the grating structure includes a plurality of first grating units arranged along a first direction and a plurality of second grating units arranged along the first direction, the first grating units and the second grating units extend along a second direction, and the plurality of first grating units and the plurality of second grating units are stacked in a one-to-one correspondence in a third direction, and the third direction is perpendicular to the first direction and the second direction;

[0014] The first grating unit and the second grating unit have different widths, and edges of the first grating unit and the second grating unit in the first direction are aligned or staggered.

[0015] In some possible implementations, the refractive index of the film is greater than or equal to 2.0 and less than or equal to 4.0; the grating structure includes a base layer and a plurality of first grating units located on the base layer, the plurality of first grating units are arranged in parallel along a first direction, and a duty cycle of the plurality of first grating units is 1.0.

[0016] In some possible implementations, the refractive index of the film is greater than or equal to 2.0 and less than or equal to 4.0; the grating structure includes a plurality of holes distributed in a concentric circle array located in the film, and the length of the holes in the circumferential direction gradually increases from the inner circle to the outer circle.

[0017] In some possible implementations, the refractive index of the film is greater than or equal to 2.0 and less than or equal to 4.0; the film includes a first layer and a second layer stacked on the first layer, the first layer has a plurality of first holes arranged in an array, the second layer has a plurality of second holes arranged in an array, and at least part of the first holes in the first layer and at least part of the second holes in the second layer are staggered.

[0018] In this implementation, the efficiency of qBIC mode excitation is enhanced by combining a high-refractive-index film (2.0-4.0) with differentiated grating elements (variations in width, position, angle, and vertical orientation). Alternating grating elements arranged in a first direction produce controllable symmetry breaking, resulting in a flat-band dispersion across the grating structure's energy bands within an incident angle range of -10 to +10 degrees.

[0019] In some possible implementations, the grating structure consists of the first grating units and the second grating units, and the first grating units and the second grating units are arranged in an alternating manner.

[0020] In the above implementation, through the periodic symmetry breaking design, multiple resonant cavities are formed on the subwavelength scale, effectively expanding the tunable range of the qBIC mode.

[0021] In some possible implementations, the grating structure further includes a plurality of third grating units arranged along the first direction, and the third grating units are located between adjacent first grating units and second grating units.

[0022] In the above implementation, the band structure is finely controlled by increasing the arrangement of grating units to increase the dimensional freedom.

[0023] In some possible implementations, the material of the thin film is amorphous silicon, titanium dioxide or molybdenum sulfide; and / or

[0024] The thickness of the film is 400 nanometers to 600 nanometers.

[0025] In the above implementation, the material or thickness of the film is selected so that the film has both high refractive index and low optical loss in the visible-near infrared band.

[0026] In some possible implementations, the photodetector includes a surface protection glass panel and a detector body, and the metasurface is attached to a side of the surface protection glass panel away from the detector body.

[0027] In the above implementation, the integrated packaging of the metasurface and the detector is achieved by bonding the surface protection glass, thereby avoiding the optical path alignment deviation of the traditional lens group.

[0028] In some possible implementations, the photodetector is a CMOS sensor, a CCD sensor, or a photodiode array.

[0029] In the above implementation, CMOS sensors are suitable for low-cost mass production, CCD sensors provide a higher dynamic range, and photodiode arrays achieve nanosecond response to meet the needs of different scenarios.

[0030] In some possible implementations, the computing module includes a processor and a memory, wherein a pre-calibrated light intensity-spectrum relationship is stored in the memory, and the processor is configured to decode the electrical signal based on the light intensity-spectrum relationship.

[0031] In the above implementation, the pre-calibration system solidifies the light intensity-spectrum mapping relationship through the memory, so that the processor can complete the spectrum reconstruction in real time.

[0032] An embodiment of the present application further provides a method for manufacturing a micro-spectrometer, comprising:

[0033] Growing a thin film on a substrate;

[0034] Spin coating photoresist on the film to form an etch resistance layer;

[0035] Spin-coating a conductive adhesive on the etching resistance layer to form an electron beam exposure resistance layer;

[0036] Transferring a pre-designed metasurface pattern to a photoresist layer using electron beam exposure, and then transferring the metasurface pattern to a thin film using dry etching to achieve metasurface patterning;

[0037] Each grating structure of the metasurface is measured and calibrated to obtain the light intensity-spectrum relationship;

[0038] transmitting the light intensity-spectrum relationship to a calculation module;

[0039] The metasurface is transferred to the surface protection glass panel of the photodetector, and a white light source is used to align the metasurface with its corresponding sensor unit area.

[0040] In the above implementation, batch preparation of complex metasurface patterns is achieved through a combined process of electron beam exposure and dry etching; the white light source calibration step greatly reduces the positioning error between the grating structure and the sensor unit, thereby improving the detection accuracy of the microspectrometer.

[0041] In some possible implementations, the substrate is made of silicon dioxide, quartz glass, or sapphire; and / or

[0042] The thickness of the substrate is 400 μm to 600 μm; and / or

[0043] The thickness of the etch resist layer is 150 nm to 250 nm; and / or

[0044] The thickness of the electron beam exposure resistance layer is 30-70 nanometers; and / or

[0045] The photoresist is PMMA, ZEP520A or hydrogen silsesquioxane;

[0046] The conductive adhesive is a metal nanoparticle-doped polymer, a carbon nanotube composite polymer or a graphene composite polymer.

[0047] The above technical features can be combined in various appropriate ways or replaced by equivalent technical features, as long as the purpose of this application can be achieved.

[0048] Compared with the prior art, the micro-spectrometer of the present application, based on a dielectric metasurface encoder, utilizes quasi-bound states of photons in a continuous medium (qBIC) to overcome the limitations of the bulky size of traditional spectrometers and the resolution-luminosity balance of micro-spectrometers. At the same time, by adjusting the grating structure, the characteristics of the symmetry breaking of the qBIC plane are used to generate photonic flat bands (Photonic Flatbands) to overcome the angle-dependent characteristics of traditional photonic crystals. Furthermore, the metasurface can be combined with a computing module as an encoder to achieve reconstruction of sparse measurement data using compressed sensing technology, thereby providing a significantly more efficient photoelectric computing system that can achieve both high sensitivity and high performance. In addition, the planar characteristics of the metasurface are fully compatible with photodetectors such as CMOS sensors and CCD sensors. For example, only one imaging lithography step is required, which will allow the device array to be directly manufactured on the imaging sensor, providing a solution for high-sensitivity snapshot spectral imaging cameras that do not require any complex optical elements or moving parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present application will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0050] Figure 1 This is a schematic diagram of the architecture of a micro-spectrometer provided in an embodiment of the present application.

[0051] Figure 2 This is a schematic diagram of a first implementation of a grating structure provided in an embodiment of the present application.

[0052] Figure 3This is the metasurface band structure and spectral response of the first implementation of the grating structure provided in the embodiments of the present application under a specific parameter setting.

[0053] Figure 4 This is a schematic diagram of a second implementation of the grating structure provided in an embodiment of the present application.

[0054] Figure 5 It is a schematic diagram of a third implementation of the grating structure provided in an embodiment of the present application.

[0055] Figure 6 It is a schematic diagram of a fourth implementation of the grating structure provided in an embodiment of the present application.

[0056] Figure 7 It is a schematic diagram of the fifth implementation of the grating structure provided in the embodiments of the present application.

[0057] Figure 8 It is a schematic diagram of a sixth implementation of the grating structure provided in an embodiment of the present application.

[0058] Figure 9 It is a schematic diagram of the seventh implementation of the grating structure provided in the embodiments of the present application.

[0059] Figure 10 It is a schematic diagram of the eighth implementation of the grating structure provided in the embodiments of the present application.

[0060] Figure 11 It is a schematic diagram of a ninth implementation of the grating structure provided in an embodiment of the present application.

[0061] Figure 12 This is a flow chart of a method for manufacturing a micro-spectrometer provided in an embodiment of the present application.

[0062] Figure 13 The embodiment of the present application provides a micro-spectrometer comprising a filter array of multiple grating structures. DETAILED DESCRIPTION

[0063] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the embodiments described are only some of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0064] The terms used in the implementation section of this application are only used to explain the specific embodiments of this application and are not intended to limit this application.

[0065] Spectrometers are among the most important instruments for materials characterization and chemical analysis. Traditional spectrometers typically consist of one or more diffraction gratings, an optical path, and a detector array. Light passes through an input slit and is directed toward the diffraction grating, which disperses the spectral components into different directions. A concave mirror focuses this scattered light onto a detector array. Advances in micro- and nanofabrication technologies have provided opportunities for developing integrated spectrometers by miniaturizing the components of these systems. Traditional benchtop spectrometers typically rely on a combination of bulky dispersive optics, long optical path lengths, detector arrays, and movable parts. These requirements, which are crucial for minimizing size, cost, and power consumption, have hindered the miniaturization of benchtop spectrometers. In recent years, miniaturized spectrometer systems have been widely developed for handheld, portable, and integrated applications, including soil and crop analysis, food industry production line monitoring, and marine / underwater scientific research. Obtaining indicative, immediate, and on-site results in these applications is a new research trend in spectrometry. Further miniaturization, down to the submillimeter scale, could open up opportunities for a wide range of applications, including lab-on-a-chip spectroscopy and other in situ and even in vitro characterization systems.

[0066] However, a major constraint in (miniaturized) spectrometer design lies in the inherent trade-off between device resolution and sensitivity. A central goal in optical device design is to utilize photons most efficiently and, in the process, extract as much information as possible from the incident radiation. This is particularly true in the quest for accurate characterization of low-intensity spectra, and is particularly important for miniaturized systems operating under uncontrolled or ambient illumination; here, the system's efficiency, or sensitivity, determines its ability to collect data with a satisfactory resolution within a given timeframe. For platforms based on traditional strategies (e.g., those using grating-mediated dispersion or filter arrays), higher resolution typically comes at the expense of the intensity of the transmitted light incident on the detector, resulting in lower signal-to-noise ratios (SNRs) and longer integration times. This limitation can be described by the resolution-luminosity product, E = RL, where R is the resolution and L is the luminosity (the throughput of light from the source to the detector), assuming that the device's efficiency, E, is constant for a given sensing area.

[0067] Metasurfaces are typically created by assembling arrays of microscopic anisotropic light scatterers (i.e., resonators, such as optical antennas). The spacing and dimensions of the antennas are much smaller than the wavelength. Therefore, due to the Huygens principle, metasurfaces can shape light wavefronts into arbitrary shapes with subwavelength resolution by inducing spatial variations in the optical response of the light scatterers. This gradient metasurface surpasses the established technology of frequency-selective surfaces made of periodic structures and extends the functionality of traditional microwave and millimeter-wave transmitting and reflecting arrays to new spectral regions. Metasurfaces can also be created using ultrathin films of optical materials with high loss. By exploiting controllable, abrupt phase shifts associated with light reflection or transmission at interfaces between lossy materials, such metasurfaces operate like optical cavities, effectively altering the device's spectrum. This presents technological opportunities in different spectral regions and their potential advantages in replacing existing optical components. Therefore, metasurfaces, as arrays of artificially designed subwavelength structures, enable full-degree-of-freedom control of light wavefronts, phase, amplitude, and polarization through precisely engineered nanoantenna units. This property enables them to replace traditional, bulky optical components such as spectrometers and polarizers, compacting complex optical systems into micron-scale thin films. This unique optical control capability and high degree of integration have attracted significant research interest in the field of optical sensors. For example, the local field enhancement effect of a metasurface can improve the detector's absorption efficiency at specific wavelengths, thereby increasing the energy utilization of incident light. Furthermore, metasurfaces can regulate the encoding of multi-dimensional information such as light intensity, polarization, and phase, enabling single-function detectors to be reused in the spatial, temporal, or frequency domains to achieve simultaneous multi-dimensional detection of incident light. This technology opens up new technical paths for both traditional optics and computational optics.

[0068] In view of this, in order to solve at least some of the technical problems existing in the prior art, such as Figure 1 As shown, an embodiment of the present application discloses a micro-spectrometer, comprising a metasurface 100, a photodetector 200 and a computing module 300. The metasurface 100 comprises a plurality of grating structures, each of which is configured to generate a qBIC mode for light of different wavelengths and output corresponding light intensities. The energy band of the grating structure exhibits flat-band dispersion within an incident angle range of -10 degrees to +10 degrees. The photodetector 200 is used to detect the light intensity output by the plurality of grating structures of the metasurface and output an electrical signal. The computing module 300 is used to decode the electrical signal to obtain spectral information. The micro-spectrometer of the present application significantly reduces the size of the spectrometer to the micron level, and can be effectively integrated into other devices or chips as a device.

[0069] In optics, qBIC (quasi-Bound State in the Continuum) is a special optical resonance mode that can achieve high localization and strong field enhancement in the continuous spectrum. Traditionally, BIC is an ideal mode existing in the continuous radiation spectrum with zero radiation loss (infinite Q factor), which usually requires strict symmetry or parameter conditions. The qBIC mode breaks the symmetry or parameter conditions of BIC (such as structural perturbations, oblique incidence, etc.) and transforms the BIC into a resonance mode with a finite but extremely high Q factor. Although its radiation loss is not zero, it is still much lower than that of ordinary resonance modes.

[0070] The grating structure exhibits flat-band dispersion within the incident angle range of -10° to +10°, indicating that its energy band hardly changes with the incident angle within this angular range, and the energy (or frequency) remains constant. This phenomenon usually originates from quasi-continuum bound states (qBICs) or symmetry-protected optical modes, which are achieved through the periodic structure or perturbation control of the grating. The formation mechanisms of flat-band dispersion may include: 1) qBIC modes remain highly localized despite slight symmetry breaking, resulting in extremely low radiation loss and insensitivity to angle; 2) band folding or mode coupling causes the light field in a specific frequency band to be strongly bound; 3) topological protection mechanisms suppress dispersion. This characteristic enables the grating to exhibit an angle-independent resonant response within the ±10° range, making it suitable for applications such as high-sensitivity sensing, nonlinear enhancement, and slow-light devices.

[0071] The unknown spectrum to be measured is filtered by the metasurface 100, and then the photodetector 200 detects the light intensity and outputs an electrical signal of the light intensity spectrum, realizing spectrum-to-light intensity encoding. The metasurface 100 and photodetector 200 can be regarded as encoders. The electrical signal is then transmitted to the computing module 300, which decodes it and obtains the reconstructed spectrum. The computing module 300 can be regarded as a light intensity-to-spectrum decoder.

[0072] Compared to traditional desktop spectrometers, the micro-spectrometer of the present application embodiment maps each point in the spectral domain (i.e., wavelength) to a corresponding point in the spatial domain (i.e., photodetector). The readings of the photodetector directly constitute the spectrum. However, the spectral resolution of a traditional desktop spectrometer varies with the distance from the grating to the detector (i.e., path length), resulting in low resolution in compact application environments. In contrast, the spectral resolution of the embodiment of the present application depends solely on the minimum area of ​​the photosensitive photoelectric device in the detector, making it suitable for use in highly integrated application environments.

[0073] The metasurface has a high Q factor, enabling filtering within an extremely narrow range. Simultaneously, the reflective strategy effectively improves the signal-to-noise ratio for low-intensity signals. Prior art narrowband filtering spectrometers face an inherent trade-off between resolution and sensitivity. Higher resolution typically comes at the expense of the intensity of the transmitted light incident on the detector, resulting in lower signal-to-noise ratios (SNRs) and longer integration times. The micro-spectrometers of the present invention utilize a reflective filtering strategy to effectively improve the signal-to-noise ratio and reduce the quantum efficiency requirements of the back-end photodetector. Furthermore, the qBIC solution provides a high-Q factor solution, enabling filtering of infinitely narrow spectral widths through fine-tuning of the structure.

[0074] Furthermore, compared to reconstruction spectrometer technology based on computational optics, the computational pressure of reconstructing the spectrum is mainly reflected in the increase in computing resources required as the resolution increases. At the same time, the adverse effect is reflected in the slower response speed of the spectrum readout, especially in low signal-to-noise ratio scenarios. The higher the mapping matrix condition number caused by the high similarity between characteristic patterns, the worse the reconstructed spectrum solution obtained. The integrated photodetector and computing module solution used in the embodiment of the present application can, on the one hand, effectively couple with existing photodetectors, and on the other hand, the directly read intensity signal can directly map the corresponding structural color spectrum, greatly reducing the demand for computing resources.

[0075] In some embodiments, the refractive index of the film is greater than or equal to 2.0 and less than or equal to 4.0. The refractive index of the film at different wavelengths can be obtained by testing equipment such as an ellipsometer.

[0076] In some embodiments, as Figure 2 As shown, the grating structure 110 includes a plurality of first grating elements 111 and a plurality of second grating elements 112 arranged along a first direction D1. The second grating elements 112 are located between two adjacent first grating elements 111. The plurality of first grating elements 111 are arranged parallel to each other, and the plurality of second grating elements 112 are arranged parallel to each other. The second grating elements 112 are arranged parallel to the first grating elements 111, and the first grating elements 111 and the second grating elements 112 have different widths. Optionally, the width X1 of the second grating elements 112 is greater than the width X2 of the first grating elements 111.

[0077] By utilizing the refractive index characteristics of thin films, simulation software can be used to design a grating structure that can generate a qBIC mode. For example, a grating structure with a length of 100 microns, a period of 800 nanometers, a first grating unit width of 168 nanometers, and a second grating unit width of 168 nanometers can generate a BIC mode at 1600 nanometers. By breaking the symmetry, making the first grating unit width 184 nanometers and the second grating unit width 152 nanometers, the energy band can be made flat-band within the range of ±10 degrees, such as Figure 3 shown.

[0078] qBIC has strong angular sensitivity and requires specific design angles to produce characteristic peaks (such as normal incidence), which greatly limits the use of qBIC spectrometers. By designing the grating structure and utilizing the optical flat-band effect, the dispersion relation of qBIC is made flat within a certain range, making it insensitive to angle and usable at all angles.

[0079] In some embodiments, as Figure 4 As shown, the grating structure 120 includes a plurality of first grating units 121 and a plurality of second grating units 122 arranged along a first direction D1, wherein the second grating units 122 are located between two adjacent first grating units 121, the plurality of first grating units 121 are arranged parallel to each other, and the plurality of second grating units 122 are arranged parallel to each other; wherein the second grating units 122 are arranged parallel to the first grating units 121, and the first grating units 121 and the second grating units 122 are staggered in a second direction D2 perpendicular to the first direction D1.

[0080] In some embodiments, as Figure 5 As shown, the grating structure 130 includes a plurality of first grating units 131 and a plurality of second grating units 132 arranged along a first direction D1. The second grating units 132 are located between two adjacent first grating units 131. The plurality of first grating units 131 are arranged parallel to each other, and the plurality of second grating units 132 are arranged parallel to each other. The first grating units 131 form a first angle Φ1 with the first direction D1, and the second grating units 132 form a second angle Φ2 with the first direction D2. The first angle Φ1 is different from the second angle Φ2.

[0081] In some embodiments, as Figure 2 、 4 5. The grating structures 110, 120, 130 are composed of the first grating units 111, 121, 131 and the second grating units 112, 122, 132, and the first grating units 111, 121, 131 and the second grating units 112, 122, 132 are arranged in an alternating manner.

[0082] In some embodiments, as Figure 6 As shown, the grating structure 140 further includes a plurality of third grating units 143 arranged along the first direction D1 , and the third grating units 143 are located between adjacent first grating units 141 and second grating units 142 .

[0083] Furthermore, in some embodiments, the grating structure may include more grating units, that is, the grating structure further includes multiple grating unit groups arranged along the first direction, and each grating unit group includes more than four different grating units.

[0084] In some embodiments, as Figure 7 As shown, the grating structure 150 includes a plurality of first grating units 151 arranged along a first direction D1 and a plurality of second grating units 152 arranged along the first direction D1. The first grating units 151 and the second grating units 152 extend along a second direction (the second direction is a direction perpendicular to the illustrated first direction D1 and a third direction D3, not shown). The plurality of first grating units 151 and the plurality of second grating units 152 are stacked one-to-one in the third direction D3, and the third direction D3 is perpendicular to the first direction D1 and the second direction. The first grating units 151 and the second grating units 152 have different widths, and the edges of the first grating units 151 and the second grating units 152 in the first direction D1 are aligned.

[0085] In some embodiments, as Figure 8 As shown, the grating structure 160 includes a plurality of first grating units 161 arranged along a first direction D1 and a plurality of second grating units 162 arranged along the first direction D1, the first grating units 161 and the second grating units 162 extending along a second direction (the second direction is a direction perpendicular to the illustrated first direction D1 and a third direction D3, not shown), the plurality of first grating units 161 and the plurality of second grating units 162 are stacked one-to-one in the third direction D3, and the third direction D3 is perpendicular to the first direction D1 and the second direction; wherein the first grating units 161 and the second grating units 162 have different widths, and the edges of the first grating units 161 and the second grating units 162 in the first direction D1 are offset.

[0086] in addition, Figure 7 and Figure 8 The grid structure can be achieved through a step-by-step etching process: first, a layer of photoresist is spin-coated and the structure of the first grating units 151 and 161 with a period of P1 and a duty cycle of F1 is completed on a glass protective plate through an exposure-etching process; then, the structure of the second grating units 152 and 162 with a period of P2 and a duty cycle of F2 is completed on another protective plate through the same exposure-etching process; finally, the grating 2 is transferred to the grating 1 through the metasurface material transfer technology and aligned ( Figure 7 implementation method) or staggering a designed parameter value ( Figure 8In this way, the symmetry breaking in the third direction D3 (vertical direction) is completed. Under suitable parameter conditions, the flat-band dispersion caused by the symmetry breaking described in this application can also be achieved.

[0087] In some embodiments, as Figure 9 As shown, the grating structure 170 includes a base layer 171 and a plurality of first grating units 172 located on the base layer 171 . The plurality of first grating units 172 are arranged in parallel along a first direction d1 , and a duty cycle of the plurality of first grating units 172 is 1.0.

[0088] Figure 9 The grid structure uses a non-complete etching method in the etching process, that is, reducing the etching time, or reducing the etching gas concentration, or reducing the etching reaction power. Under suitable parameter conditions, the flat band dispersion caused by the symmetry breaking described in this application can also be achieved.

[0089] In some possible implementations, such as Figure 10 As shown, the grating structure includes a plurality of holes distributed in a concentric circle array on the film, and the length of the holes in the circumferential direction gradually increases from the inner circle to the outer circle.

[0090] It should be noted that Figure 10 The design process of the lattice structure can include (1) designing a C6-symmetric photonic crystal plate PCL-1 with suitable structural parameters (period P, circular hole radius R). (2) rotating PCL-1 around the central axis by an angle theta to obtain the photonic crystal plate PCL-2. (3) performing a Boolean operation on the union of PCL-1 and PCL-2 to obtain the photonic crystal plate PCL-3, which is the desired final photonic crystal plate.

[0091] For example, Figure 10 The preparation process of the grid structure can include: (1) using a silicon-on-insulator (SOI) substrate to prepare a twisted lattice nanocavity. Electron beam lithography is used to define the device pattern in which two sets of nanoholes with twisted angles are drawn onto the electron beam resist. (2) Using an inductively coupled plasma etching process, holes are etched on the top silicon layer. Buffered hydrofluoric acid is used to etch away the buried oxide layer to form a suspended membrane for cavity testing. (3) In the two sets of twisted photonic graphene lattices with a 4.41° nanocavity, the nanohole diameter is 220nm and the lattice constant is 500nm. In the two sets of twisted photonic graphene lattices with a 0.596° nanocavity, the nanohole diameter is 210nm and the lattice constant is 460nm. The thickness of the silicon membrane is 220nm.

[0092] In some possible implementations, such as Figure 11As shown, the film includes a first layer and a second layer stacked on the first layer, the first layer has a plurality of first holes arranged in an array, the second layer has a plurality of second holes arranged in an array, and at least part of the first holes in the first layer and at least part of the second holes in the second layer are staggered.

[0093] It should be noted that Figure 11 The design process of the lattice structure can include (1) designing a C6-symmetric photonic crystal plate PCL-1 with suitable structural parameters (period P, circular hole radius R); (2) rotating PCL-1 around the central axis by an angle theta to obtain a crystal plate PCL-2; (3) preparing PCL-1 and PCL-2 separately and stacking them in two layers.

[0094] In the above implementation, a metasurface composed of a structure with flat-band dispersion can be achieved under specific structural parameters through a periodic arrangement. Alternatively, a metasurface composed of a 2D or 3D grating structure with symmetry-breaking artificial defects can be used.

[0095] In some embodiments, the thin film is made of amorphous silicon, titanium dioxide, or molybdenum sulfide. All of these materials are high-refractive-index materials, which have a stronger ability to bind light and can more significantly control light properties such as phase, amplitude, and polarization at subwavelength scales. High-refractive-index materials can also enhance the local field effect of light in nanostructures, making the interaction between light and matter more intense. This enhancement effect helps improve the sensitivity of the spectrometer, enabling it to more effectively detect low-intensity incident light signals.

[0096] In some embodiments, the film has a thickness of 400 nm to 600 nm. Alternatively, the film may have a thickness of approximately 400 nm, 420 nm, 440 nm, 460 nm, 480 nm, 500 nm, 520 nm, 540 nm, 560 nm, 580 nm, or 600 nm.

[0097] In some embodiments, the photodetector comprises a surface protective glass panel and a detector body, with the metasurface attached to the side of the surface protective glass panel facing away from the detector body. This implementation makes the metasurface fully compatible with the photodetector, requiring only a single photolithography patterning step. This allows for direct fabrication of device arrays onto imaging sensors, significantly simplifying the manufacturing process and providing a viable solution for high-sensitivity snapshot spectral imaging cameras.

[0098] In some embodiments, the photodetector is a CMOS sensor, a CCD sensor, or a photodiode array.

[0099] In some embodiments, the calculation module includes a processor and memory. The memory stores a pre-calibrated light intensity-spectrum relationship, and the processor is configured to decode the electrical signal based on the light intensity-spectrum relationship. This effectively reduces the computational resource requirements and computational cost of calculating spectral information, while also improving the accuracy of spectral calculations.

[0100] On the other hand, Figure 12 As shown, the embodiment of the present application also discloses a method for manufacturing a micro-spectrometer, comprising:

[0101] S1. Growing a thin film on a substrate.

[0102] Optionally, the substrate is made of silicon dioxide, quartz glass, or sapphire. Optionally, the substrate has a thickness of 400 to 600 microns. Optionally, the film may have a thickness of approximately 400, 420, 440, 460, 480, 500, 520, 540, 560, 580, or 600 microns. For example, an amorphous silicon film approximately 500 nanometers thick may be grown on a 500 micron silicon dioxide substrate using PECVD (plasma enhanced chemical vapor deposition).

[0103] S2. Spin-coating photoresist on the film to form an etching resistance layer.

[0104] Optionally, the thickness of the etch-resist layer is between 150 nanometers and 250 nanometers. Optionally, the photoresist is PMMA, ZEP520A, or hydrogen silsesquioxane. Optionally, the thickness of the etch-resist layer is approximately 150 nanometers, 160 nanometers, 170 nanometers, 180 nanometers, 190 nanometers, 200 nanometers, 210 nanometers, 220 nanometers, 230 nanometers, 240 nanometers, or 250 nanometers. For example, a 200-nanometer photoresist PMMA film can be spin-coated using a spin-coater as the etch-resist layer.

[0105] S3, spin-coating a conductive adhesive on the etching resistance layer to form an electron beam exposure resistance layer.

[0106] Optionally, the thickness of the electron beam exposure resistance layer is 30-70 nanometers. Optionally, the conductive adhesive is a metal nanoparticle-doped polymer, a carbon nanotube composite polymer, or a graphene composite polymer. Optionally, the thickness of the electron beam exposure resistance layer is approximately 30 nanometers, 40 nanometers, 50 nanometers, 60 nanometers, or 70 nanometers. For example, a spin-coater can be used to spin-coat approximately 50 nm of conductive adhesive as the electron beam exposure resistance layer.

[0107] S4. Use electron beam exposure to transfer the pre-designed metasurface pattern to the photoresist layer, and then use dry etching to transfer the metasurface pattern to the thin film to achieve metasurface patterning.

[0108] For example, electron beam (EBL) exposure can be used to transfer the designed metasurface pattern to a photoresist layer, and dry etching can be used to transfer the photoresist pattern to an amorphous silicon film to achieve metasurface patterning. Other steps, such as removing the photoresist layer, are also included and will not be described in detail here.

[0109] S5. Measure and calibrate each grating structure of the metasurface 100 to obtain a light intensity-spectrum relationship.

[0110] For example, each individual grating structure can be measured and calibrated using angle-resolved spectroscopy to ensure that the band gap of the flat-band dispersion is within the designed wavelength range.

[0111] S6. Transmit the light intensity-spectrum relationship to the calculation module 300.

[0112] S7. Transfer the metasurface to the surface protection glass panel of the photodetector, and use a white light source to align the metasurface with its corresponding sensor unit area.

[0113] For example, the metasurface can be transferred to a CMOS surface protection glass panel, and a white light source can be used to align the metasurface with its corresponding sensor unit area. The sensor area can be encoded so that it maps the corresponding structural spectrum, completing the decoding function of the computational spectrometer.

[0114] The system can also include spectrum testing and reconstruction steps. Specifically, the light to be measured is incident on the integrated micro-spectrometer, and the light intensity information corresponding to each sensor area is read out, completing the spectrum-to-light intensity encoding. The encoded data is then transmitted to a computer and decoded using a calibrated decoder.

[0115] Figure 13 The present invention relates to a filter array composed of multiple grating structures of a micro-spectrometer manufactured using the above method.

[0116] In general, the embodiments of the present application provide a micro-spectrometer based on the metasurface qBIC (quasi-bound states of photons in continuous media) mode and the flat-band characteristics of photons. Through the coordinated work of the metasurface, photodetector and computing module, the inherent contradiction between resolution and sensitivity of traditional spectrometers is overcome, and miniaturization, high performance and angle-insensitive spectral detection are achieved. Specifically, it includes: (1) metasurface design: a metasurface containing multiple grating structures is used, and the qBIC mode is excited by combining a high refractive index film (2.0-4.0) with differentiated grating units (different widths, positions or angles), so that the energy band of the grating structure exhibits flat-band dispersion within the incident angle range of -10° to +10°, achieving angle-insensitive response. (2) System integration: the metasurface is directly bonded to the photodetector (such as CMOS, CCD), and the computing module decodes the electrical signal based on the pre-calibrated light intensity-spectrum relationship to complete the spectral information extraction.

[0117] Through the above technical means, the embodiments of the present application can achieve the following technical effects:

[0118] (1) High sensitivity and high performance: The high Q factor of the qBIC mode is used to achieve narrowband filtering, and the reflective strategy is combined to improve the signal-to-noise ratio of low-intensity signals, solving the problem of "high resolution at the expense of light intensity" in traditional spectrometers.

[0119] (2) Angle insensitivity: Through the flat-band dispersion design, the spectrometer can work stably within the incident angle range of ±10°, expanding the application scenarios.

[0120] (3) Miniaturization and integration: The subwavelength structure of the metasurface is directly compatible with photodetectors, eliminating the need for complex optical components and significantly reducing the size, allowing it to be integrated into chips or portable devices.

[0121] (4) Low cost and efficient computing: Using mature detectors such as CMOS, combined with pre-calibrated decoding algorithms, reduces hardware costs and computing resource requirements, and achieves real-time spectral reconstruction.

[0122] Although the present application is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the present application. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the present application as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in conjunction with other described embodiments.

Claims

1. A miniature spectrometer, characterized in that: include: A metasurface comprising a thin film having a plurality of grating structures, wherein the plurality of grating structures are configured to generate qBIC modes for light of different wavelengths and output corresponding light intensities, wherein the energy band of the grating structure exhibits flat-band dispersion within an incident angle range of -10 degrees to +10 degrees; a photodetector, configured to detect the light intensity output by the plurality of grating structures of the metasurface and output an electrical signal; A calculation module is used to decode the electrical signal to obtain spectral information.

2. The micro-spectrometer according to claim 1, characterized in that The refractive index of the film is greater than or equal to 2.0 and less than or equal to 4.0; the grating structure includes a plurality of first grating units and a plurality of second grating units arranged along a first direction, the second grating units are located between two adjacent first grating units, the plurality of first grating units are arranged parallel to each other, and the plurality of second grating units are arranged parallel to each other; wherein, The second grating units are arranged in parallel with the first grating units, and the first grating units and the second grating units have different widths; The second grating units are arranged in parallel with the first grating units, and the first grating units and the second grating units are staggered in a second direction perpendicular to the first direction; or The first grating unit forms a first angle with the first direction, and the second grating unit forms a second angle with the first direction, and the first angle is different from the second angle.

3. The micro-spectrometer according to claim 1, characterized in that The refractive index of the film is greater than or equal to 2.0 and less than or equal to 4.0; the grating structure includes a plurality of first grating units arranged along a first direction and a plurality of second grating units arranged along the first direction, the first grating units and the second grating units extend along a second direction, and the plurality of first grating units and the plurality of second grating units are stacked in a one-to-one correspondence in a third direction, and the third direction is perpendicular to the first direction and the second direction; The first grating unit and the second grating unit have different widths, and edges of the first grating unit and the second grating unit in the first direction are aligned or staggered.

4. The micro-spectrometer according to claim 1, wherein: The refractive index of the film is greater than or equal to 2.0 and less than or equal to 4.0; the grating structure includes a base layer and a plurality of first grating units located on the base layer, the plurality of first grating units are arranged in parallel along a first direction, and the duty cycle of the plurality of first grating units is 1.

0.

5. The micro-spectrometer according to claim 1, characterized in that: The refractive index of the film is greater than or equal to 2.0 and less than or equal to 4.0; the grating structure includes a plurality of holes distributed in a concentric circle array located in the film, and the length of the holes in the circumferential direction gradually increases from the inner circle to the outer circle.

6. The micro-spectrometer according to claim 1, characterized in that: The refractive index of the film is greater than or equal to 2.0 and less than or equal to 4.0; the film includes a first layer and a second layer stacked on the first layer, the first layer has a plurality of first holes arranged in an array, the second layer has a plurality of second holes arranged in an array, and at least part of the first holes in the first layer and at least part of the second holes in the second layer are staggered.

7. The micro-spectrometer according to any one of claims 1 to 6, characterized in that: The material of the film is amorphous silicon, titanium dioxide or molybdenum sulfide; and / or The thickness of the film is 400 nanometers to 600 nanometers.

8. The micro-spectrometer according to any one of claims 1 to 6, characterized in that: The photodetector includes a surface protection glass panel and a detector body, and the metasurface is attached to the side of the surface protection glass panel away from the detector body; wherein the photodetector is a CMOS sensor, a CCD sensor or a photodiode array.

9. The micro-spectrometer according to any one of claims 1 to 6, characterized in that: The calculation module includes a processor and a memory, wherein a pre-calibrated light intensity-spectrum relationship is stored in the memory, and the processor is used to decode the electrical signal based on the light intensity-spectrum relationship.

10. The method for manufacturing a micro-spectrometer according to any one of claims 1 to 6, characterized in that: include: Growing a thin film on a substrate; Spin coating photoresist on the film to form an etch resistance layer; Spin-coating a conductive adhesive on the etching resistance layer to form an electron beam exposure resistance layer; Transferring a pre-designed metasurface pattern to a photoresist layer using electron beam exposure, and then transferring the metasurface pattern to a thin film using dry etching to achieve metasurface patterning; Each grating structure of the metasurface is measured and calibrated to obtain the light intensity-spectrum relationship; transmitting the light intensity-spectrum relationship to a calculation module; Transferring the metasurface to the surface protection glass panel of the photodetector, and aligning the metasurface with its corresponding sensor unit area using a white light source; Wherein, the material of the substrate is silicon dioxide, quartz glass or sapphire; and / or The thickness of the substrate is 400 μm to 600 μm; and / or The thickness of the etch resist layer is 150 nm to 250 nm; and / or The thickness of the electron beam exposure resistance layer is 30-70 nanometers; and / or The photoresist is PMMA, ZEP520A or hydrogen silsesquioxane; The conductive adhesive is a metal nanoparticle-doped polymer, a carbon nanotube composite polymer or a graphene composite polymer.

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