CN207263300U - A kind of spectrometer based on super surface texture - Google Patents

Abstract

The utility model discloses a spectrometer based on a metasurface structure. The spectrometer includes an incident slit, a metasurface structure, a photoelectric detector array, and a spectrum signal output device. Its working process is: light enters the metasurface structure from the incident slit, and the incident slit is used to reduce the interference of stray light from the outside; the metasurface structure uses periodically arranged elliptical nanopillars of different sizes to form a Phase distribution is required to achieve light splitting, so that incident light of different wavelengths is focused on different positions of the photodetector array, and the spectral map is obtained on the spectral signal output device by using the output intensity signals at different positions. The utility model greatly simplifies the structure of the traditional spectrometer, and meanwhile has the characteristics of miniaturization, portability and high resolution.

Description

A spectrometer based on metasurface structure

technical field

The utility model relates to the field of spectrum detection, in particular to a spectrometer based on a metasurface structure.

Background technique

The essence of a spectrometer is a "spectroscopy" instrument. Now the mainstream way to realize the spectroscopic function is to use a grating as a dispersion component to separate the light of different wavelengths in space, and use an array detector to receive and output the spectrum. Spectroscopic instruments are the basic testing equipment for spectral analysis. They have important applications in various fields such as industry, agriculture, biology, medicine, environment, health, energy, national defense, astronomy, and extraterrestrial life detection. At the same time, the performance level of spectroscopic instruments directly affects our country's basic research, and is of great significance to the exploration and discovery of new materials, new energy, and the unknown world. With the rapid development of global technology and economy, as well as the huge pressure on the environment and resources, the demand for small-scale high-resolution, high-sensitivity, wide-band intelligent spectroscopic instruments is becoming more and more urgent.

After retrieval, the invention patent with the publication number CN101493357A discloses a wide-band spectrometer, which includes light, a light source collimation system, a polarizer, a polarization rotator composed of optically active substances, an analyzer, a detector and data acquisition System, the light source collimation system is composed of two prisms, and the light source, light source collimation system, polarizer, polarization rotator composed of optically active material, analyzer and detector are arranged in sequence on the light path from the light source to the detector. The invention patent with the publication number CN106441572A discloses a compact high-throughput spectrometer, which includes an incident slit, a reflective grating, a set of lens groups with collimating and imaging functions, and a detector; the incident light enters the slit , after being collimated by the lens group, the light is diffracted and split by the reflection grating, and then converged and imaged on the detector by the lens group.

But the structure that above-mentioned patent adopts is all more complicated, and volume is big, is not convenient for portability.

Contents of the invention

In view of the defects of the prior art, the purpose of this utility model is to provide a spectrometer based on a metasurface structure, which uses a metasurface structure with a period smaller than the wavelength to simultaneously realize the functions of a spectroscopic grating and a converging mirror, greatly reducing the structural volume, It is convenient for instrument portability.

To achieve the above objectives, the utility model provides a spectrometer based on a metasurface structure, which includes an incident slit, a metasurface structure, a photodetector array and a spectral signal output device.

A spectrometer based on a metasurface structure is characterized in that it is composed of an incident slit, a metasurface structure, a photodetector array and a spectral signal output device; its working process is: a light beam enters the metasurface from the incident slit structure, the phase distribution generated by the metasurface lens can focus light of different wavelengths at different positions of the photodetector array, and use the output intensity signals at different positions to obtain the spectrogram of the measured light on the spectral signal output device .

The metasurface structure is composed of a metasurface unit structure and a substrate whose period is smaller than the wavelength of the incident light, wherein the metasurface unit structure is composed of elliptical cylinders with a major axis radius b and a minor axis radius a arranged in a period Λ along the x and y directions, and the incident light The propagation direction of light is the z direction; the substrate is silicon dioxide material, and the elliptical column is silicon material.

The values of the major axis radius and the minor axis radius of the elliptical cylinder in each period of the metasurface structure are determined according to the following phase formula: , where λ _d is the wavelength of the incident light, f is the focal length of the metasurface lens, x _f is the component of the focal length in the x direction, y _f is the component of the focal length in the y direction, z _{f is} the focal length in z components in the direction.

The utility model uses the metasurface structure to produce different phase distributions for light of different wavelengths, so that different wavelengths can be focused on different positions on the surface of the photodetector array to realize the functions of light splitting and imaging, and a small metasurface structure with a specific phase distribution It replaces the spectroscopic grating and converging mirror in the optical structure of the traditional spectrometer, which makes the structure simple and compact, reduces the volume, and facilitates the portability of the instrument.

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the utility model.

Fig. 2 is a schematic diagram of an elliptical cylinder and a base structure within a single period of the present invention.

Fig. 3 is a top view of a metasurface structure designed by an embodiment of the present invention.

Fig. 4 is the calculated lateral displacement of different wavelengths incident on the spectrometer along the z direction according to the utility model.

Detailed ways

As shown in Figure 1, a spectrometer based on a metasurface structure is characterized in that it consists of an incident slit (1), a metasurface structure (2), a photodetector array (3) and a spectral signal output device (4) ; Its working process is: the light beam enters the metasurface structure (2) from the incident slit (1), and the phase distribution generated by the metasurface lens can focus light of different wavelengths on the photodetector array (3 ) at different positions, using the output intensity signals at different positions, to obtain a spectrogram of the measured light on the spectral signal output device (4). Where: the propagation direction of the incident light is the z direction.

The incident slit (1) is used to guide the light to be detected into the spectrometer while reducing the entry of stray light from the outside.

The metasurface structure (2) includes a substrate and elliptical cylinders arranged periodically along the x and y directions on the substrate, and the phases generated after the light beam is transmitted through the elliptical cylinders of different sizes are different. When nano-silicon chips of different sizes are arranged periodically and form a complete 2π phase, the focused imaging of the beam can be realized. At the same time, beams of different wavelengths at the same position (that is, the same coordinates (x, y)) will produce different phase changes after passing through an elliptical cylinder of the same size, so they will be focused at different positions in the subsequent optical path and produce different displacements. spectroscopic effect. The desired phase satisfies that the phase at coordinates (x, y) is Ψ (x, y), , λ _d is the wavelength of the incident light, f is the focal length of the metasurface off-axis lens, x _f is the component of the focal length in the x direction, y _f is the component of the focal length in the y direction, z _{f is} the focal length component in the z direction. The above formula is the focusing formula of the three-dimensional spherical lens. The beam is focused on a point, also known as point focusing. The beam of the three-dimensional cylindrical lens is focused on a line, also known as line focusing, and the focusing formula is or , the focal line is along the y-direction or the x-direction, respectively. Compared with the spherical focusing lens, the structure of the cylindrical focusing lens is that the metasurface structure is arranged according to the focusing phase formula along the direction perpendicular to the focal line, and arranged periodically in the direction parallel to the focusing line. According to the above phase distribution requirements, combined with FDTD Solutions software simulation, the phases generated by the elliptical cylinder under different structural sizes can be obtained, so that the size of the elliptical cylinder in each period can be determined.

The photodetector array (3) is used to receive light signals from different positions.

The spectral signal output device (4) is used to read the information transmitted from the photoelectric signal detector array and process the output.

As shown in Figure 2, the metasurface unit structure in a single period is an elliptical cylinder (5), the major axis radius is b, and the minor axis radius is a; the substrate (6) is silica material, and the elliptical cylinder (5) is silicon material, the period in the x and y directions is Λ.

In order to make the above purpose, features and advantages of the utility model more obvious and easy to understand, the specific implementation of the utility model will be described in detail below in conjunction with the accompanying drawings.

Example 1:

The metasurface structure (2) in the spectrometer based on the metasurface structure designed in this embodiment is a three-dimensional cylindrical lens, and the line focusing formula is , the focal line is along the y direction. Working wavelength λ _d =1550 nm, focal length f =8910 nm, x _f =6300 nm, z _f =6300 nm, period Λ =900nm. Table 1 shows the calculated correspondence between the phase Ψ and the position x and the dimensions a and b of the elliptical cylinder in the case of the above parameters. According to the data in Table 1, each metasurface unit structure is arranged as shown in Figure 3, where The x direction is arranged according to the unit number in the figure, and the y direction is arranged according to the period. Only 4 periods are drawn in the figure to produce the effect of light splitting. Figure 4 shows the calculation results of the lateral displacement generated by the spectrometer when different wavelengths are incident. It can be seen that different wavelengths will be focused at different positions to complete the spectroscopic function. lateral displacement is defined as the displacement perpendicular to the focal axis (the line connecting the center of the structure and the focal point).

Table 1

This embodiment greatly simplifies the structure, is conducive to the miniaturization and portability of the instrument, and has the characteristics of high precision.

The embodiment discussed above is only a description of the preferred implementation of the present utility model, and is not intended to limit the concept and scope of the present utility model. Various modifications and improvements made in the technical solution should fall into the scope of protection of the utility model, and the technical content required by the utility model has been fully recorded in the claims.

Claims (3)

1. a kind of spectrometer based on super surface texture, it is characterised in that by entrance slit（1）, super surface texture（2）, photoelectricity Detector array（3）And spectral signal follower（4）Composition；Its course of work is：Light beam to be measured is by entrance slit（1）Into The super surface texture（2）, the light of different wave length can be focused on by the photoelectricity by the phase distribution of super surface lens generation Detector array（3）At diverse location, using the output intensity signal on diverse location, in spectral signal follower（4）On obtain Obtain the spectrogram of light to be measured.

A kind of 2. spectrometer based on super surface texture according to claim 1, it is characterised in that the super surface texture by Cycle be less than lambda1-wavelength super surface cell structure and substrate form, wherein super surface cell structure for major axis radius b with The cylindroid of minor axis radius a is rearranged along x, y direction with periods lambda, and the direction of propagation of incident light is z directions；Substrate is dioxy Silicon nitride material, cylindroid are silicon materials.

3. a kind of spectrometer based on super surface texture according to claim 1, it is characterised in that the super surface texture is every The numerical value of cylindroid major axis radius and minor axis radius in a cycle is determined according to following phase formula：<math display = 'block'> <mtable columnalign='left' linebreak='true'> <mtr> <mtd> <mi>&amp;phiv;</mi> <mtext>（</mtext> <mi>x</mi> <mtext>）</mtext> <mo>=</mo> <mfrac> <mrow> <mn>2</mn> <mtext>π</mtext> </mrow> <msub> <mi>&amp;lambda;</mi> <mi>d</mi> </msub> </mfrac> <mo stretchy='false'>(</mo> <mi>f</mi> <mo>&amp;minus;</mo> <msqrt> <mrow> <msup> <mrow> <mo stretchy='false'>(</mo> <mi>x</mi> <mo>&amp;minus;</mo> <msub> <mi>x</mi> <mi>f</mi> </msub> <mo stretchy='false'>)</mo> </mrow> <mn>2</mn> </msup> <mo>+</mo> <msup> <mrow> <mo stretchy='false'>(</mo> <mi>y</mi> <mo>&amp;minus;</mo> <msub> <mi>y</mi> <mi>f</mi> </msub> <mo stretchy='false'>)</mo> </mrow> <mn>2</mn> </msup> <mo>+</mo> <msup> <msub> <mi>z</mi> <mi>f</mi> </msub> <mn>2</mn> </msup> </mrow> </msqrt> <mo stretchy='false'>)</mo> </mtd> </mtr> <mtr> <mtd> <mrow></mrow> </mtd> </mtr> </mtable> </math>, wherein λ_dFor lambda1-wavelength, f is the super surface lens Focal length, x_fFor the component of the focal length in the x direction, y_fFor the component of the focal length in y-direction, z_fFor the focal length in a z-direction Component.