A miniature dispersive spectrometer based on metasurface lenses

Abstract

This application relates to a miniature dispersive spectrometer based on a metasurface lens, belonging to the field of spectral analysis. It includes, sequentially arranged along the optical path: an entrance slit for receiving the beam of light to be measured emitted from an incident light source; a double-sided metasurface lens, composed of a transparent substrate and a first metasurface and a second metasurface located on opposite surfaces of the substrate; the first metasurface is a phase distribution microstructure with collimation function, and the second metasurface is a phase distribution microstructure with dispersive function; an integrated light-blocking structure including a micro-aperture aperture and a light-blocking plate matched with the double-sided metasurface lens, the double-sided metasurface lens being embedded in this structure; and a detector, disposed on the dispersive focal plane of the double-sided metasurface lens, for receiving the dispersed optical signal. This miniature dispersive spectrometer, through its design, can be applied to different wavelength ranges and reduces the required components, thereby minimizing the overall size of the spectrometer.

Description

Technical Field

[0001] This application belongs to the field of spectral analysis, and specifically relates to a miniature dispersive spectrometer based on metasurface lenses. Background Technology

[0002] Spectroscopic analysis, as a core method for detecting the composition of substances, has important applications in environmental monitoring, biomedicine, and food safety. Traditional dispersive systems mainly employ prism dispersion or grating diffraction schemes, which suffer from the following technical bottlenecks:

[0003] First, the overall size of the equipment is relatively large. Prism dispersion relies on geometric optical path to achieve dispersion, and the axial dimension of prism systems generally exceeds 50mm, making it difficult to meet the miniaturization requirements of portable devices. In traditional spectrometers, the dispersion module accounts for more than 60% of the total volume.

[0004] Second, it requires high integration precision and has a complex optical path. Traditional spectrometers typically consist of a light source, entrance slit, collimating mirror, beam splitter, focusing lens, exit slit, filter, aperture, mirror, modulator, and detector along the optical path from the light source to the detector. The optical path structure is complex and requires high assembly and alignment precision.

[0005] Third, dispersion efficiency and resolution are limited. The nonlinearity of the refractive index of the prism material leads to a sharp drop in dispersion efficiency in the long-wavelength region (e.g., the dispersion efficiency of BK7 glass drops by 40% after 600 nm), and it is difficult to achieve both wide wavelength range and high resolution due to Abbe number limitations. Typical commercial prism spectrometers have a resolution of less than 5 nm in the 400-900 nm wavelength range.

[0006] As can be seen from the above, traditional spectrometers have complex structures, require many optical components, are large in size, are not easy to make lightweight and portable, and have limited dispersion efficiency and resolution.

[0007] In conclusion, how to simplify and lighten spectrometers while still maintaining a wide bandwidth is a topic worthy of study in the field of spectral analysis. Utility Model Content

[0008] This application provides a miniature dispersive spectrometer based on metasurface lenses. By designing the spectrometer, it can be applied to different wavelength ranges and reduces the required components, thereby reducing the overall size of the spectrometer, so as to at least solve the above-mentioned technical problems existing in the prior art.

[0009] This application provides a miniature dispersive spectrometer based on metasurface lenses, including: an entrance slit arranged sequentially along the optical path for receiving the beam of light to be measured emitted by an incident light source;

[0010] A double-sided metasurface lens is composed of a light-transmitting substrate and a first metasurface and a second metasurface located on the two surfaces of the substrate, respectively; the first metasurface is a phase distribution microstructure with collimation function, and the second metasurface is a phase distribution microstructure with dispersion function.

[0011] An integrated light-blocking structure includes a micro-perforated aperture and a light-blocking plate that match a double-sided metasurface lens, wherein the double-sided metasurface lens is embedded in the structure;

[0012] The detector is set on the dispersive focal plane of the double metasurface lens and is used to receive the optical signal after beam splitting. The light beam emitted from the entrance slit is collimated by the first metasurface and then split by the second metasurface. Light of different wavelengths is focused to different positions on the detector.

[0013] In one embodiment, the microstructure of the first metasurface is an array of elliptical nanopillars arranged in concentric rings, and the microstructure of the second metasurface is an array of gradually changing periodic rectangular nanopillars.

[0014] In one embodiment, the aperture of the micro-aperture of the integrated light-blocking structure is matched with the light-transmitting aperture of the superlens, and the light-blocking plates are distributed according to the dispersion angle and spacing of each superlens to block crosstalk light paths.

[0015] In one embodiment, the substrate of the double-sided metasurface lens is made of quartz glass.

[0016] In one embodiment, the detector is an area array photoelectric sensor, the photosensitive surface of which coincides with the dispersive focal plane of the double-sided metasurface lens. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the miniature dispersive spectrometer in the embodiments of this application;

[0018] Figure 2 This is a schematic diagram of a double-sided superlens in an embodiment of this application;

[0019] Figure 3 This is a schematic diagram of the integrated light-blocking structure in an embodiment of this application;

[0020] Explanation of reference numerals in the attached figures:

[0021] 1. Incident light source; 2. Entrance slit; 3. Double-sided metasurface lens; 31. First metasurface; 32. Second metasurface; 4. Integrated light-blocking structure; 41. Micro-aperture aperture; 42. Light-blocking plate; 5. Detector. Detailed Implementation

[0022] The present application will now be described in further detail with reference to the accompanying drawings.

[0023] In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0024] This application discloses a miniature dispersive spectrometer based on metasurface lenses, comprising an incident light source 1, an incident slit 2, a double-sided metasurface lens 3, an integrated light-blocking structure 4, and a detector 5 arranged sequentially along the optical path.

[0025] Incident light source 1 is located at the entrance of the spectrometer, providing the spectrometer with the beam to be measured.

[0026] The entrance slit 2 is located a short distance from the incident light source 1, allowing the incident light to enter the spectrometer and receive the beam of light to be measured emitted by the incident light source.

[0027] The double-sided metasurface lens 3 is located at a certain distance from the entrance slit 2 and is embedded in the integrated light-blocking structure 4. The double-sided metasurface lens 3 consists of a light-transmitting substrate and a first metasurface 31 and a second metasurface 32 located on the two surfaces of the substrate, respectively. The first metasurface 31 is a phase distribution microstructure with collimation function, and the second metasurface 32 is a phase distribution microstructure with dispersion function. The microstructure of the first metasurface 31 can be an elliptical nanopillar array arranged in concentric rings, and the microstructure of the second metasurface 32 can be a gradient periodic rectangular nanoarray.

[0028] The integrated light-blocking structure 4 includes a micro-aperture 41 and a light-blocking plate 42 that match the double-sided metasurface lens 3. The double-sided metasurface lens 3 is embedded in this structure. The aperture of the micro-aperture of the integrated light-blocking structure 4 matches the light-passing aperture of the double-sided metasurface lens 3. The light-blocking plate 42 is arranged according to the dispersion angle and spacing of each double-sided metasurface lens 3 to block crosstalk light paths.

[0029] The detector 5 is set on the dispersive focal plane of the double-sided metasurface lens 3 and is used to receive the light signal after beam splitting. It is a planar array photoelectric sensor, and the photosensitive surface coincides with the dispersive focal plane of the double-sided metasurface lens 3. The light beam emitted from the entrance slit 2 is collimated by the first metasurface 31 and then split by the second metasurface 32. Light of different wavelengths is focused to different positions of the detector 5.

[0030] Detector 5 is located at the focal length corresponding to different wavelengths of the superlens array and is used to detect the intensity of the light beam at different wavelengths.

[0031] The working process of the spectrometer based on metasurface lenses is as follows: the beam to be tested enters the metasurface lens array structure through the entrance slit 2. The metasurface lens array structure is composed of double-sided microstructures. After the beam to be tested passes through the slit, it first comes into contact with the collimated light formed by the phase distribution of the microstructure of the first metasurface 31. Then the beam enters the dispersive effect formed by the phase distribution of the microstructure of the second metasurface 32, focusing light of different wavelengths at different positions of the detector 5 to obtain the spectral pattern of the beam to be tested.

[0032] In the above technical solution, the first metasurface 31 microstructure is composed of elliptical nanopillars distributed in concentric rings (major axis 80-180nm, minor axis 60-120nm, height 220nm), and incident light collimation (divergence angle <0.5°) is achieved using a quadratic phase distribution. The second metasurface 32 microstructure is composed of gradient periodic rectangular nanogrooves (groove width 50-150nm, depth 300nm, period 200-400nm), and dispersion is achieved by applying a linear gradient phase (dispersion rate 2.8nm / μm@532nm). The substrate material is low birefringence quartz glass (refractive index n=1.46@633nm), and the double-sided metastructure is fabricated using a combination of atomic layer deposition (ALD) and electron beam lithography.

[0033] In the above technical solution, the integrated light-blocking structure 4 consists of a micro-aperture 41 and a light-blocking plate 42. The micro-aperture 41 is designed according to the required aperture size of each superlens dispersion array, and the light-blocking plate 42 is designed according to the required angle and distance of each superlens dispersion array to prevent light crosstalk. The integrated light-blocking structure 4 is integrally formed by 3D printing SLM process.

[0034] The working principle of any of the above miniature dispersive spectrometers is as follows:

[0035] After the incident light source 1 passes through the incident slit 2, it first contacts the micro-array structure of the first metasurface 31 of the double-sided metasurface lens 5 embedded in the integrated light-blocking structure 4 to form a collimated light path. After reaching the micro-array structure of the second metasurface 32, it undergoes dispersion. Then, it passes through the micro-aperture 41 at a certain angle through the light-blocking plate 42 and reaches the detector 5 for processing to form a spectrum.

[0036] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A metasurface-lens-based miniature dispersive spectrometer, characterized in that, Including those arranged sequentially along the optical path: An entrance slit (2) is used to receive the beam of light to be measured emitted by the incident light source (1); The double-sided metasurface lens (3) is composed of a light-transmitting substrate and a first metasurface (31) and a second metasurface (32) located on the two surfaces of the substrate respectively; the first metasurface (31) is a phase distribution microstructure with collimation function, and the second metasurface (32) is a phase distribution microstructure with dispersion function. An integrated light-blocking structure (4) includes a micro-aperture (41) and a light-blocking plate (42) that match the double-sided metasurface lens (3), wherein the double-sided metasurface lens (3) is embedded in the structure; The detector (5) is set on the dispersive focal plane of the double-sided metasurface lens (3) and is used to receive the optical signal after beam splitting; wherein, the light beam emitted from the entrance slit (2) is collimated by the first metasurface (31) and then enters the second metasurface (32) for beam splitting, and different wavelengths of light are focused to different positions of the detector (5).

2. The miniature dispersive spectrometer of claim 1, wherein: The microstructure of the first metasurface (31) is an array of elliptical nanopillars arranged in concentric rings, and the microstructure of the second metasurface (32) is a gradually changing periodic rectangular nanoarray.

3. The miniature dispersive spectrometer according to claim 1, characterized in that: The aperture of the integrated light-blocking structure (4) is matched with the light-passing aperture of the superlens, and the light-blocking plates are arranged according to the dispersion angle and spacing of each superlens to block crosstalk light paths.

4. The miniature dispersive spectrometer according to claim 1, characterized in that: The substrate of the double-sided metasurface lens (3) is made of quartz glass.

5. The miniature dispersive spectrometer according to claim 1, characterized in that: The detector (5) is an area array photoelectric sensor, whose photosensitive surface coincides with the dispersive focal plane of the double-sided metasurface lens (3).

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