Light splitting device and preparation method thereof

Abstract

The light splitting device provided by the embodiment of the invention comprises a grating used for filtering first incident light, and the transmissivity of the grating to polarized light in a specific direction of the first incident light is greater than the transmissivity to polarized light in other directions of the first incident light; the optical filter and the grating are arranged in a stacked mode, the optical filter is used for filtering the second incident light, and the transmissivity of the optical filter to light with at least one specific wavelength in the second incident light is larger than the transmissivity of the optical filter to light with other wavelengths in the second incident light. According to the invention, the grating and the optical filter are stacked, and simultaneous spectral and polarized light splitting of incident light is realized by using the polarization light splitting effect of the grating and the spectral light splitting effect of the optical filter; moreover, the grating and the optical filter are integrated, the size is small, the structure is compact, the stability is high, and integration is easy, so that the problems of huge size, discrete structure, poor stability and difficulty in integration of an assembly system for simultaneously acquiring spectral information and polarization information in the prior art are solved.

Description

Technical Field

[0001] The present application relates to the technical field of spectroscopic devices, and in particular to a spectroscopic device and a method for preparing the same. Background Art

[0002] Spectral spectroscopy technology has a wide range of applications in agriculture and forestry, geological exploration, environmental monitoring, medical diagnosis, space remote sensing and other fields; at the same time, polarization spectroscopy technology is widely used in camouflage recognition, underwater imaging, maritime target recognition and other fields. Combining spectral spectroscopy technology with polarization spectroscopy technology can achieve detection in complex environments and obtain more dimensional light field information, which has broad application prospects. The simultaneous acquisition of spectral information and polarization information is achieved through a spectroscopic device that can perform spectral spectroscopy and polarization spectroscopy at the same time.

[0003] In the prior art, in order to simultaneously obtain spectral information and polarization information, it is necessary to assemble an independent spectral splitter and an independent polarization control device. This assembly system is bulky, discrete in structure, has poor stability, and is difficult to integrate. Summary of the invention

[0004] In view of this, the present application provides a spectrometer and a method for preparing the same to solve the problems in the prior art of an assembly system composed of independent spectral spectrometers and independent polarization control devices being bulky, discrete in structure, poor in stability, and difficult to integrate.

[0005] In a first aspect, an embodiment of the present application provides a spectroscopic device, comprising: a grating for filtering a first incident light, the transmittance of the grating to polarized light of a specific direction of the first incident light being greater than the transmittance to polarized light of other directions of the first incident light; and a filter stacked with the grating for filtering a second incident light, the transmittance of the filter to light of at least one specific wavelength in the second incident light being greater than the transmittance to light of other wavelengths of the second incident light.

[0006] In combination with the first aspect, in certain implementations of the first aspect, the filter includes: a first reflective layer; an intermediate layer, stacked with the first reflective layer; and a second reflective layer, wherein the second reflective layer is located on a side of the intermediate layer away from the first reflective layer, and the grating is located on a side of the second reflective layer away from the intermediate layer.

[0007] In combination with the first aspect, in certain implementations of the first aspect, the first reflective layer and / or the second reflective layer includes a multilayer optical film, wherein the multilayer optical film is configured to be an alternating stack of first refractive index film layers and second refractive index film layers, and the refractive index of the first refractive index film layer is greater than the refractive index of the second refractive index film layer.

[0008] In combination with the first aspect, in some implementations of the first aspect, the intermediate layer includes a plurality of stepped portions arranged in parallel, and the thicknesses of the plurality of stepped portions are not completely the same, so as to form a plurality of spectral channels.

[0009] In combination with the first aspect, in certain implementations of the first aspect, the thickness of the intermediate layer is set based on an application wavelength of the filter and a refractive index of the intermediate layer.

[0010] In combination with the first aspect, in some implementations of the first aspect, the grating is a one-dimensional rectangular metal grating.

[0011] In combination with the first aspect, in certain implementations of the first aspect, a grating period of the grating is less than a quarter of an applied wavelength of the filter.

[0012] In combination with the first aspect, in some implementations of the first aspect, a grating strip width of the grating is one tenth to nine tenths of a grating period of the grating.

[0013] In the second aspect, an embodiment of the present application provides a method for preparing a spectroscopic device, comprising: coating a filter on a substrate, wherein the filter is used to filter a second incident light, and the transmittance of the filter to at least one specific wavelength of light in the second incident light is greater than the transmittance to other wavelengths of light in the second incident light; and coating a grating on a side of the filter away from the substrate, wherein the grating is used to filter a first incident light, and the transmittance of the grating to polarized light in a specific direction of the first incident light is greater than the transmittance to polarized light in other directions of the first incident light.

[0014] In combination with the second aspect, in certain implementations of the second aspect, a filter is coated on a substrate, including: coating a first reflective layer on the substrate; coating an intermediate layer on a side of the first reflective layer away from the substrate, the intermediate layer including a plurality of step portions arranged in parallel, the thicknesses of the plurality of step portions being not completely the same, so as to form a plurality of spectral channels; coating a second reflective layer on a side of each step portion away from the first reflective layer.

[0015] The spectroscopic device provided in the embodiment of the present application stacks the grating and the filter, uses the polarization splitting effect of the grating to perform polarization splitting on the incident light incident to the grating, and uses the spectral splitting effect of the filter to perform spectral splitting on the incident light incident to the filter, thereby achieving simultaneous spectral and polarization splitting. The spectroscopic device provided in the embodiment of the present application uses the grating as a polarization splitting device and the filter as a spectral splitting device, and integrates the grating and the filter into one, which has a small size, a compact structure, strong stability, and is easy to integrate, thereby solving the problems of large size, discrete structure, poor stability, and difficulty in integration of the assembly system for simultaneously obtaining spectral information and polarization information in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 Shown is a schematic structural diagram of a spectrometer provided in one embodiment of the present application.

[0018] Figure 2 Shown is a schematic structural diagram of a filter provided in one embodiment of the present application.

[0019] Figure 3 Shown is a schematic structural diagram of a first reflective layer and / or a second reflective layer provided in one embodiment of the present application.

[0020] Figure 4 Shown is a schematic structural diagram of a filter including an intermediate layer with multiple stepped portions provided in one embodiment of the present application.

[0021] Figure 5 The present invention provides an embodiment of the present invention including Figure 4 Schematic diagram of the structure of the spectrometer of the middle filter 2.

[0022] Figure 6 It is a schematic structural diagram of incident light entering a spectrometer including a substrate provided by an exemplary embodiment of the present application.

[0023] Figure 7 Shown is a curve diagram of polarized light transmission spectra and polarization extinction ratio of incident light entering TE and TM polarization modes provided by an exemplary embodiment of the present application.

[0024] Figure 8 Shown is a schematic curve diagram of polarized light transmission spectra and polarization extinction ratio of incident light entering TE and TM polarization modes provided by another exemplary embodiment of the present application.

[0025] Fig. 9 Shown is a schematic curve diagram of polarized light transmission spectra and polarization extinction ratio of incident light entering TE and TM polarization modes provided by yet another exemplary embodiment of the present application.

[0026] Fig.10 The figure is a schematic flow chart of a method for preparing a spectroscopic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The features, structures or characteristics described in the exemplary embodiments of the present application may be combined in one or more embodiments in any suitable manner. In addition, the drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated descriptions will be omitted.

[0028] Spectral features are generated by the interaction between electromagnetic waves and objects. Since different atoms and molecules can emit or absorb light of different wavelengths, the information of the material can be effectively detected by analyzing the unique reflection, absorption and radiation spectra and emission peaks of the research object in a specific spectral range. Spectral spectroscopy technology has a wide range of applications in agriculture, forestry, geological exploration, environmental monitoring, medical diagnosis, space remote sensing and other fields. Polarization is an important parameter of light waves in addition to intensity, frequency and phase. It is a new dimension for obtaining information on the optical properties of matter. There are significant differences in the polarization states of light waves reflected and radiated by different objects or different states of the same object. Polarization spectroscopy technology is widely used in camouflage recognition, underwater imaging, maritime target recognition and other fields. Combining spectral spectroscopy technology with polarization spectroscopy technology can realize detection in complex environments and obtain more dimensional light field information, which has broad application prospects. The simultaneous acquisition of spectral information and polarization information is achieved by a spectroscopic device that can perform spectral spectroscopy and polarization spectroscopy at the same time.

[0029] In the prior art, obtaining spectral information and polarization information simultaneously requires assembling an independent spectral spectrometer and an independent polarization control device. Such an assembly system is bulky, discrete in structure, poor in stability, and difficult to integrate. Therefore, the present application integrates an optical microcavity and a grating structure to provide a spectral and polarization simultaneous spectrometer that is small in size, simple in structure, good in stability, and easy to integrate.

[0030] Figure 1 Shown is a schematic structural diagram of a spectrometer provided in one embodiment of the present application.

[0031] like Figure 1As shown, the spectrometer device includes a grating 1 and a filter 2, and the grating 1 and the filter 2 are stacked. Among them, the grating 1 performs polarization splitting on the incident light (i.e., the first incident light) incident to the grating 1, and the transmittance of the grating 1 to the polarized light in a specific direction of the incident light is greater than the transmittance to the polarized light in other directions of the incident light, so as to achieve polarization splitting of the incident light incident to the grating 1. The light after being filtered by the grating 1 is incident to the filter 2, and the filter 2 performs spectral splitting on the incident light (i.e., the second incident light) incident to the filter 2, and the transmittance of the filter 2 to at least one specific wavelength of the incident light is greater than the transmittance to the light of other wavelengths of the incident light, so as to achieve spectral splitting of the incident light incident to the filter 2, and further, ultimately achieve simultaneous spectral and polarization splitting of the incident light.

[0032] In an embodiment of the present application, the grating 1 can be any grating that can achieve a transmittance of polarized light in a specific direction of incident light greater than the transmittance of polarized light in other directions of incident light, and the number of gratings can be one or more. When the number of gratings is multiple, the multiple gratings can be arranged in a plane or in a three-dimensional arrangement, and the present application does not impose specific restrictions on this. The filter 2 can be any filter that can filter light of at least one specific wavelength, and the number of filters can be one or more. When the number of filters is multiple, the filters can be connected in series in multiple stages. When the spectroscopic device includes multiple gratings or multiple filters, the filters and gratings can be alternately stacked, and the present application does not impose specific restrictions on this.

[0033] In addition, in the embodiment of the present application, a specific wavelength refers to the application wavelength of the filter 2, and multiple specific wavelengths refer to the application band of the filter 2 containing multiple specific wavelengths. The application wavelength in the present application is not specifically limited and can be selected according to actual conditions, and can belong to a wavelength in one of the visible band, near infrared band, medium-wave infrared band, long-wave infrared band, etc.

[0034] In the embodiment of the present application, the grating 1 performs polarization splitting on the incident light, which means that after filtering or polarization splitting by the grating 1, the flux of polarized light in a specific direction of the incident light is greater than the flux of polarized light in other directions of the incident light. In addition, the filter 2 performs spectral splitting on the incident light, which means that after filtering or spectral splitting by the filter 2, the flux of light of at least one specific wavelength of the incident light is greater than the flux of light of other wavelengths of the incident light.

[0035] In some embodiments, after being filtered by the grating 1, light with a specific polarization direction is obtained. Further, the light with a specific polarization direction is incident on the filter 2, and finally light with a specific polarization direction and a specific wavelength is obtained through the spectral splitting effect of the filter 2. Exemplarily, the grating 1 is a one-dimensional grating, and the polarized light with a specific direction is polarized light (TM polarized light) whose electric vector vibration direction is perpendicular to the grating direction of the grating 1.

[0036] The spectroscopic device provided in the embodiment of the present application stacks the grating and the filter, uses the polarization splitting effect of the grating to perform polarization splitting on the incident light incident to the grating, and uses the spectral splitting effect of the filter to perform spectral splitting on the incident light incident to the filter, thereby achieving simultaneous spectral and polarization splitting. The spectroscopic device provided in the embodiment of the present application uses the grating as a polarization splitting device and the filter as a spectral splitting device, and integrates the grating and the filter into one, which has a small size, compact structure, strong stability, easy integration, and a wide range of applications, thereby solving the problems of large size, discrete structure, poor stability, and difficulty in integration of the assembly system for simultaneously obtaining spectral information and polarization information in the prior art.

[0037] Figure 2 FIG. 1 is a schematic diagram of the structure of a filter provided by an embodiment of the present application. Figure 2 As shown, the filter 2 includes a first reflective layer 21, an intermediate layer 22 and a second reflective layer 23. The intermediate layer 22 and the first reflective layer 21 are stacked, the second reflective layer 23 is located on the side of the intermediate layer 22 away from the first reflective layer 21, and the grating 1 is arranged on the side of the second reflective layer 23 away from the intermediate layer 22. The first reflective layer 21, the intermediate layer 22 and the second reflective layer 23 together form a resonant cavity, and the resonant cavity can be used to control the characteristics of the oscillating light beam in the cavity, including the wavelength, to achieve the spectral splitting function and filter the incident light into at least one specific wavelength of light. In addition, the filter of this structure can be used in a wider band, and the splitting ability is not limited by distance, and it is easy to integrate at zero distance, which is conducive to the preparation of micro-spectral equipment.

[0038] Figure 3 Shown is a schematic structural diagram of a first reflective layer and / or a second reflective layer provided in one embodiment of the present application.

[0039] In the filter 2 of the above structure, the first reflective layer 21 may include one or more layers of optical thin films, and the second reflective layer 23 may include one or more layers of optical thin films, and the material of the optical thin films may be metal or non-metal. In some embodiments, the first reflective layer 21 and / or the second reflective layer 23 include a single layer of optical thin film, and the material of the optical thin film is metal. In other embodiments, such as Figure 3As shown, the first reflective layer 21 and / or the second reflective layer 23 include a multilayer optical film, wherein the multilayer optical film is configured as a first refractive index film layer and a second refractive index film layer stacked alternately, the refractive index of the first refractive index film layer being greater than the refractive index of the second refractive index film layer; the materials of the first refractive index film layer and the second refractive index film layer are materials that are optically transparent in the working band of the optical filter 2, wherein the materials of the first refractive index film layer and the second refractive index film layer include but are not limited to halides, oxides, sulfides and semiconductor materials. The first reflective layer 21 and / or the second reflective layer 23 are reflective layers including a multilayer optical film, and compared with the case of including a single layer of optical film, the first reflective layer 21 and / or the second reflective layer 23 including a multilayer optical film has a higher reflectivity, and is more likely to strengthen the same light waves and cancel out opposite light waves, thereby obtaining a filter 2 with better filtering performance.

[0040] In some embodiments, the intermediate layer 22 may be a vacuum layer or a dielectric layer. In some embodiments, the intermediate layer 22 is a dielectric layer, and the material of the dielectric layer 22 includes but is not limited to halides, oxides, sulfides, and semiconductor materials. In other embodiments, the intermediate layer 22 may be composed of the same medium as the first refractive index film layer or the second refractive index film layer, or may be composed of a medium different from the first refractive index film layer and the second refractive index film layer.

[0041] In some embodiments, the materials of the first reflective layer 21, the intermediate layer 22, and the second reflective layer 23 of the filter 2 are all non-metallic materials, and the peak transmittance of the full dielectric film filter 2 is greater than the peak transmittance of the metal-dielectric film filter 2. In other embodiments, the first reflective layer 21 and / or the second reflective layer 23 of the full dielectric film filter 2 include a multilayer optical film, wherein the multilayer optical film is configured as a first refractive index film layer and a second refractive index film layer stacked alternately, and the refractive index of the first refractive index film layer is greater than the refractive index of the second refractive index film layer. The manufacturing process of the full dielectric film filter 2 is relatively simple, and it has a high transmittance and reflectivity, and the optical performance is stable, and it is not easily affected by environmental factors such as temperature and humidity. It can effectively filter incident light of multiple wavelengths and has a wide range of applications.

[0042] Exemplarily, the film system expression of filter 2 is (LH) m xH(HL) m-1 H or (LH) m xL(HL) m , wherein H represents the first refractive index film layer; L represents the second refractive index film layer; m is the number of times the high refractive index film layer and the low refractive index film layer are alternately stacked, and exemplarily, m>2; xL or xH is the film system expression of the intermediate layer 22, with the first reflective layer 21 and the second reflective layer 23 on both sides, and x is the multiple of the first / second refractive index film layer (H / L), and exemplarily, x≥2.

[0043] Figure 4 FIG. 1 is a schematic diagram of the structure of a filter including a plurality of stepped portions provided in one embodiment of the present application. Figure 5 The present invention provides an embodiment of the present invention including Figure 4 Schematic diagram of the structure of the spectrometer with a medium filter.

[0044] like Figure 4 and Figure 5 As shown, the first reflective layer 21, the middle layer 22 and the second reflective layer 23 of the filter 2 together form a resonant cavity. The distance between the first reflective layer 21 and the second reflective layer 23 determines the wavelength restriction of the resonant cavity. Therefore, the application wavelength of the filter 2, that is, the specific wavelength finally filtered by the filter 2, can be changed by adjusting the distance.

[0045] Therefore, the application wavelength of the filter 2 can be changed by adjusting the thickness of the intermediate layer 22. In some embodiments, the intermediate layer 22 includes a plurality of stepped portions arranged in parallel, each of which has the same thickness, but the thicknesses of the plurality of stepped portions are not completely the same. The plurality of stepped portions can be arranged in sequence according to their respective thicknesses, or can be arranged in a random order according to actual application requirements. Figure 4 As shown, among the multiple step portions of the intermediate layer 22, each step portion has a different thickness, and is arranged in parallel in descending order of thickness. In the spectroscopic device, the upper and lower surfaces of each step portion are provided with a first reflective layer 21 and a second reflective layer 23, and each step portion and the two reflective layers can form a resonant cavity, and each resonant cavity with different thicknesses can filter a specific wavelength of light. Therefore, the filter 2 can filter multiple specific wavelengths of light by providing step portions of different thicknesses to achieve multi-spectral spectrometry, that is, to form a filter with different passband peaks, so that the spectroscopic device provided in the embodiment of the present application (such as Figure 5 The optical efficiency and performance of the spectrometer can be improved by meeting the requirements of multi-spectral spectrometry.

[0046] In some embodiments, the thickness of the intermediate layer 22 is set based on the application wavelength of the filter 2 and the refractive index of the intermediate layer 22. When the incident light satisfies 2nd=mλ (where n is the refractive index of the material of the intermediate layer 22; d is the thickness of the intermediate layer 22; m is the interference secondary, which is a certain value; λ is the application wavelength of the resonance cavity corresponding to the intermediate layer 22), the resonance cavity corresponding to the intermediate layer 22 has a maximum transmittance for light of a specific wavelength, that is, light of the application wavelength of the corresponding resonance cavity, so that the light of the specific wavelength can be transmitted through the corresponding resonance cavity to the greatest extent, so as to achieve the best performance of the filter 2.

[0047] In some embodiments, the optical thickness of the first refractive index film layer 21 and the optical thickness of the second refractive index film layer 23 are equal, and both are one-fourth of the application wavelength of the filter 2. The optical thickness refers to the ratio of the actual length that the incident light passes through a certain medium to the length of the medium in a vacuum due to the change in the refractive index of the medium. At this time, the interference effect between the two reflective layers and the middle layer on the application wavelength is the largest, and the maximum transmittance and minimum reflectance can be achieved to achieve the best performance of the filter.

[0048] The structure of the filter 2 in the spectroscopic device provided in the embodiment of the present application is described in detail above. The grating 1 in the spectroscopic device provided in the embodiment of the present application will be described in detail below in conjunction with the drawings in the embodiment of the present application.

[0049] The spectrometer device includes a grating 1, which performs polarization splitting on the incident light incident to the grating 1, and the transmittance of the grating 1 to polarized light in a specific direction of the incident light is greater than the transmittance to polarized light in other directions of the incident light, so as to achieve polarization splitting of the incident light incident to the grating 1. The grating 1 is any grating having the above-mentioned polarization splitting function. Conventional polarizers are either large in size and cannot be miniaturized and integrated, or the manufacturing process is relatively complicated, and the application wavelength and application angle are small. In the present application, the optical structure for polarization splitting is a grating, which has a small size, good polarization performance, and is easy to integrate. In addition, when the filter 2 includes a first reflective layer 21, an intermediate layer 22 and a second reflective layer 23, the preparation process of the two is compatible with the existing semiconductor process, which is conducive to the preparation of the spectrometer device.

[0050] Exemplarily, the grating 1 is a one-dimensional or two-dimensional grating. Exemplarily, the grating 1 is one of a rectangular grating, a trapezoidal grating, and a triangular grating. Exemplarily, the material of the grating is one of a metal or a dielectric material. In some embodiments, the material of the grating is one of Au, Ag, Cu, Al, etc. or an alloy thereof. In some embodiments, the grating 1 is a one-dimensional rectangular metal grating, which is simple to manufacture and can be very small in size, such as nanometer level, and has better polarization performance than other gratings.

[0051] In some embodiments, the grating 1 is a one-dimensional grating, and the grating 1 includes a plurality of bars, and the plurality of bars are arranged in parallel and equidistantly. Polarized light (TE polarized light) whose electric vector vibration direction is parallel to the bar direction of the grating 1 is reflected, while polarized light (TM polarized light) whose electric vector vibration direction is perpendicular to the bar direction of the grating 1 can be transmitted, thereby completing the selection of the polarization state.

[0052] Specifically, according to the equivalent medium theory, the grating 1 can be regarded as an equivalent medium layer, and the TE polarized light and the TM polarized light have different equivalent refractive indices. When TE polarized light is incident, the equivalent refractive index of the grating layer is Where n0 and n1 are the refractive indices of air and grating 1, respectively, f is the duty cycle of grating 1, and for the applied wavelength, n TE It has a large imaginary part of the refractive index, which is equivalent to the metal layer, so TE polarized light is reflected in large quantities; when TM polarized light is incident, the equivalent refractive index of the grating layer is Where n0 and n1 are the refractive indices of air and grating 1, respectively, f is the duty cycle of grating 1, and n TM It has a very small imaginary part of the refractive index, which is equivalent to a dielectric layer, so a large amount of TM polarized light can be transmitted out of the grating 1, thereby completing the selection of the polarization state.

[0053] In some embodiments, the grating 1 is a two-dimensional grating. Due to the symmetry of the grating structure, it can be equivalent to a superposition of two one-dimensional metal gratings with the same physical mechanism and the grating strips along one axis and another axis perpendicular to it. Then, TE polarized light can be equivalently regarded as TM polarized light for the grating strips along one axis. Therefore, most of the incident light in any linear polarization state between TM polarized light and TE polarized light can be highly transmitted, thereby completing the selection of polarization state.

[0054] The grating period of the grating is p, which is the length from one refractive index change point to an adjacent refractive index change point; the grating width is w, and the grating thickness is h.

[0055] In some embodiments, the grating period p of the grating 1 is smaller than the applied wavelength of the filter 2, and the grating bars will diffract the incident light. At this time, the grating period determines the angle and intensity of the diffraction. The grating period is smaller than the applied wavelength of the filter, which can ensure that the incident light is correctly diffracted, and within a certain range, the smaller the grating period p, the higher the polarization extinction ratio of the grating 1 to polarized light (that is, the ratio of the transmittance of TM polarized light with the electric vector vibration direction perpendicular to the grating bar direction to the transmittance of TE polarized light with the electric vector vibration direction parallel to the grating bar direction). Exemplarily, the grating period p of the grating 1 is smaller than one-quarter of the applied wavelength of the filter 2 to obtain a higher polarization extinction ratio, increase the proportion of TM polarized light in the light passing through the grating 1, and enhance the polarization splitting effect of the grating 1. Further, the polarization splitting effect of the splitting device is enhanced.

[0056] In some embodiments, the transmittance of polarized light (TE polarized light) whose electric vector vibration direction is parallel to the grating bar direction of grating 1 decreases sharply with the increase of the grating bar width w, and the transmittance of polarized light (TM polarized light) whose electric vector vibration direction is perpendicular to the grating bar direction decreases with the increase of the grating bar width w at a rate much lower than that of TE polarized light, so the polarization extinction ratio of grating 1, that is, the polarization extinction ratio of the spectral and polarization simultaneous spectroscopic device, can be adjusted by adjusting the grating bar width w of grating 1. Exemplarily, the grating bar width w is one tenth to nine tenths of the grating period p. At this point, the structure of the grating is appropriate and the polarization extinction is relatively high to ensure the polarization spectroscopic effect of the grating, and further, to improve the polarization extinction ratio and optical efficiency of the spectroscopic device.

[0057] In some embodiments, the transmittance of polarized light (TE polarized light) whose electric vector vibration direction is parallel to the grating bar direction of grating 1 decreases sharply with the increase of grating height h, and the transmittance of polarized light (TM polarized light) whose electric vector vibration direction is perpendicular to the grating bar direction decreases at a rate much lower than that of TE polarized light with the increase of grating height h, so the polarization extinction ratio of grating 1 can also be adjusted by adjusting the grating height h of grating 1. The grating height h can be set according to actual conditions, and this application does not make any specific limitation.

[0058] Figure 6 FIG. 1 is a schematic diagram showing a structure of a spectroscopic device including a substrate provided by an exemplary embodiment of the present application when incident light is incident on the device. Figure 6 As shown, a substrate 3 may also be provided on the side of the filter 2 of the spectrometer away from the grating to play a supporting role. The substrate 3 may be any optical medium material that is transparent at the application wavelength, including but not limited to fused quartz glass, K9 glass, ZK6 glass, BK glass, optical glass, polymethyl methacrylate, polycarbonate, gemstone, zinc sulfide, zinc selenide, magnesium fluoride, silicon wafer or germanium wafer. The type of substrate 3 may be selected according to actual conditions, and is not specifically limited in this application. The substrate 3 may be prepared separately or may be an optical element on other devices. For example, the grating 1 and the filter 2 may be integrated into an anti-reflection coating, a thin-film interference filter and / or other elements to improve performance and / or function.

[0059] The structure of the spectrometer provided by the embodiment of the present application is described in detail above. The spectrometer provided by the embodiment of the present application stacks the grating and the filter, uses the polarization splitting effect of the grating to perform polarization splitting on the incident light incident to the grating, and uses the spectral splitting effect of the filter to perform spectral splitting on the incident light incident to the filter, thereby realizing simultaneous spectral and polarization splitting. The spectrometer provided by the embodiment of the present application uses the grating as a polarization splitting device and the filter as a spectral splitting device, and integrates the grating and the filter into one, which has a small size, a compact structure, and is easy to integrate. The shape, size, and applicable band can be freely designed, which improves the reliability, stability, application range, and optical efficiency of the spectrometer, thereby solving the problems of large size, discrete structure, poor stability, and difficulty in integration of the assembly system for simultaneously obtaining spectral information and polarization information in the prior art.

[0060] For ease of understanding, the effects of the spectrometer provided in the embodiments of the present application will be specifically described below in conjunction with three exemplary embodiments.

[0061] In an exemplary embodiment, the application wavelength of the spectrometer is λ0=4 μm, and the spectrometer includes a grating and a filter stacked with the grating. The filter is a full dielectric FP (Fabry-Perot) filter, and the film system expression is (LH) 4 (LL) 2 (HL) 4 , where H is the first refractive index film layer with an optical thickness of λ0 / 4, and its material is Si; L is the second refractive index film layer with an optical thickness of λ0 / 4, and its material is SiO. The first refractive index film layer and the second refractive index film are alternately stacked to form the first reflection layer and the second reflection layer respectively; the middle layer is composed of two layers of the second refractive index film layer. The grating is a one-dimensional rectangular metal grating with a grating period of p = 200nm, a grating width of w = 140nm, a grating height of h = 200nm, and the material is metal Au.

[0062] When incident light enters the spectroscopic device of this exemplary embodiment, the TE and TM polarized light transmission spectra and the polarization extinction ratio curves are as follows: Figure 7 As shown. The solid line represents the transmittance of TM polarized light, the dashed line represents the transmittance of TE polarized light, and the dashed line represents the polarization extinction ratio of the spectrometer (TM polarized light transmittance / TE polarized light transmittance). When light is incident, at the application wavelength λ0 = 4μm, the transmittance of TM polarized light is about 97%; the half-height width is 17nm, and the polarization extinction ratio (TM polarized light transmittance / TE polarized light transmittance) is as high as 10 6 Therefore, the optical splitter of this exemplary embodiment has good spectrum and polarization splitting capabilities.

[0063] In another exemplary embodiment, the application wavelength of the spectrometer is λ0=10.6 μm, and the spectrometer includes a grating, a filter stacked with the grating, and a substrate arranged on one side of the filter principle grating. The material of the substrate is Ge. The filter is a full dielectric FP (Fabry-Perot) filter, and the film system expression is (LH) 4 (LL) 2 (HL) 4 , where H is the first refractive index film layer with an optical thickness of λ0 / 4, and its material is Ge; L is the second refractive index film layer with an optical thickness of λ0 / 4, and its material is ZnS. The first refractive index film layer and the second refractive index film layer are alternately stacked to form a first reflection layer and a second reflection layer respectively; the middle layer is composed of two layers of the second refractive index film layer. The grating is a one-dimensional rectangular metal grating with a grating period of p = 1000nm, a grating width of w = 760nm, a grating height of h = 200nm, and the material is metal Au. The film system expression of the entire material can be written as Sub|(LH) 4 (LL) 2 (HL) 4 M.

[0064] When incident light enters the spectroscopic device of this exemplary embodiment, the TE and TM polarized light transmission spectra and the polarization extinction ratio curves are as follows: Figure 8 As shown. The solid line represents the transmittance of TM polarized light, the dashed line represents the transmittance of TE polarized light, and the dotted line represents the polarization extinction ratio of the spectrometer (TM polarized light transmittance / TE polarized light transmittance). When light is incident, at the application wavelength λ0 = 10.6μm. The transmittance of TM polarized light is about 96%; the half-height width is 31nm, and the polarization extinction ratio (TM polarized light transmittance / TE polarized light transmittance) is as high as 10 5 Therefore, the optical splitter of this exemplary embodiment has good spectrum and polarization splitting capabilities.

[0065] Finally, in an exemplary embodiment, the application band of the spectrometer is 10.2 μm to 11.2 μm, taking 5 spectral channels as an example. The spectrometer includes a grating, a filter stacked with the grating, and a substrate arranged on one side of the filter principle grating. The material of the substrate is Ge. The filter is a full dielectric FP (Fabry-Perot) filter, and the middle layer thereof includes 5 step portions arranged in parallel, and the application wavelength λ0 of each step portion is different to form 5 spectral channels. The film system expression of the filter is (LH) 4 (xL) 2 (HL) 4, where H is the first refractive index film layer with an optical thickness of λ0 / 4, and its material is Ge, L is the second refractive index film layer with an optical thickness of λ0 / 4, and its material is ZnS, and x is a multiple of the low refractive index film layer L with an optical thickness of λ0 / 4, where the value of x is 1.8-2.2. Exemplarily, the values ​​of x are 1.8, 1.9, 2, 2.1, and 2.2, respectively. The grating is a one-dimensional rectangular metal grating with a grating period p=1000nm, a grating width w=760nm, a grating height h=200nm, and the material is metal Au.

[0066] When incident light enters the spectroscopic device of this exemplary embodiment, the TE and TM polarized light transmission spectra and the polarization extinction ratio curves are as follows: Fig. 9 As shown. The solid line represents the transmittance of TM polarized light, the dotted line represents the transmittance of TE polarized light, and the dashed line represents the polarization extinction ratio of the spectrometer (TM polarized light transmittance / TE polarized light transmittance). When light is incident, within the application wavelength range of 10.2μm to 11.2μm, the transmittance of TM polarized light is greater than 80%; the half-height width is about 30nm, and the polarization extinction ratio (TM polarized light transmittance / TE polarized light transmittance) is as high as 10 5 Therefore, the optical splitter of this exemplary embodiment has good spectrum and polarization splitting capabilities.

[0067] Fig.10 FIG. 1 is a schematic diagram of a method for preparing a spectroscopic device provided in an embodiment of the present application. Fig.10 As shown, the method for preparing the spectroscopic device provided in the embodiment of the present application includes:

[0068] S1001, coating a filter on a substrate, wherein the filter is used to filter the second incident light, and the transmittance of the filter to at least one specific wavelength of the second incident light is greater than the transmittance to other wavelengths of the second incident light.

[0069] Specifically, the filter can be any type of filter with spectral splitting effect, and the grating can be any type of grating with polarization splitting effect. The type and preparation process of the substrate are not specifically limited in the embodiments of the present application. The substrate can be specially used for preparation by this method, or it can be an optical component on other equipment. After the preparation is completed, the substrate of the spectrometer can be retained, or it can be peeled off the spectrometer according to actual needs.

[0070] In some embodiments, when coating the filter on the substrate, a thin film coating method such as molecular beam epitaxy (MBE), physical vapor deposition (PVD) or chemical vapor deposition (CVD) is used. For example, the film system expression of coating the film on the substrate in sequence is (LH) m xH(HL) m-1 H or (LH)m xL(HL) m structure to form an all-dielectric FP filter, wherein H represents the first refractive index film layer; L represents the second refractive index film layer; m is the number of times the high refractive index film layer and the low refractive index film layer are alternately stacked, and m>2; x is the multiple of the first / second refractive index film layer (H / L).

[0071] S1002, coating a grating on a side of the filter away from the substrate, wherein the grating is used to filter the first incident light, and the transmittance of the grating to polarized light of a specific direction of the first incident light is greater than the transmittance to polarized light of other directions of the first incident light.

[0072] In some embodiments, when a grating is coated on the side of the filter away from the substrate, a method of stripping the coating after lithography is adopted. The optional lithography methods include laser direct writing, electron beam direct writing, soft X-ray lithography, stepper lithography, etc., and the coating methods include physical vapor deposition (PVD), chemical vapor deposition (CVD), etc., and then the grating on the side of the filter away from the substrate is obtained by removing the glue through a stripping process, thereby completing the preparation of the spectrometer.

[0073] The principle of solving the problem by the spectrometer prepared by the above preparation method embodiment is the same as that of the above spectrometer embodiment. Therefore, the parameters, materials, or implementation of the preparation method embodiment can refer to the above spectrometer embodiment, and the repeated parts will not be repeated.

[0074] In some embodiments, coating a filter on a substrate includes: coating a first reflective layer on the substrate; coating an intermediate layer on a side of the first reflective layer away from the substrate, the intermediate layer including a plurality of step portions arranged in parallel, the thicknesses of the plurality of step portions being not completely the same, so as to form a plurality of spectral channels; coating a second reflective layer on a side of each step portion away from the first reflective layer, so as to complete the preparation of the filter.

[0075] Specifically, the plating of the first reflective layer, the intermediate layer including a plurality of stepped portions arranged in parallel, and the second reflective layer can be achieved by any method that can achieve this purpose.

[0076] In some embodiments, the steps for preparing a filter including an intermediate layer with multiple stepped portions are as follows:

[0077] Depositing a first reflective layer on the substrate, illustratively, the first reflective layer is a metal reflective mirror;

[0078] Spin-coating an electron beam mask glue with a uniform thickness on a side of the first reflective layer away from the substrate;

[0079] Drawing a pattern according to the structure of the intermediate layer, and performing electron beam exposure according to the pattern;

[0080] After electron beam exposure, uniform development is performed to obtain a photoresist material with step-wise thickness changes at different positions, so as to form an intermediate layer including a plurality of step portions arranged in parallel;

[0081] A second reflective layer is deposited on the intermediate layer. Exemplarily, the second reflective layer is a metal reflective mirror to form a filter.

[0082] The metal-dielectric film filter can be obtained through the above steps, and the filter includes a middle layer with multiple stepped portions to form multiple light splitting channels.

[0083] In some other embodiments, the steps for preparing the optical filter including the intermediate layer with multiple stepped portions are as follows:

[0084] Plating a first reflective layer on the substrate;

[0085] Plating a material required for preparing an intermediate layer on a side of the first reflective layer away from the substrate to form a material layer to be processed, wherein the thickness of the material layer to be processed is the maximum value of the thicknesses of the multiple step portions;

[0086] Spin-coating a UV photoresist with uniform thickness on a side of the material layer to be processed away from the first reflective layer, then outputting different doses of UV light at different positions of the photolithography pattern for exposure, and obtaining photoresist mask layers of different thicknesses after development, wherein the photolithography pattern is designed based on an intermediate layer including a plurality of stepped portions arranged in parallel;

[0087] Using an etching process to transfer the step morphology of the photoresist mask layer to the material layer to be processed thereunder, so as to form an intermediate layer including a plurality of step portions arranged in parallel;

[0088] A second reflective layer is plated on a side of the intermediate layer away from the first reflective layer to form a filter.

[0089] The first reflective layer and the second reflective layer can be plated according to actual needs, and this embodiment does not specifically limit this.

[0090] In some embodiments, including 2 N The steps for preparing the filter of the middle layer of the stepped part are as follows:

[0091] Plating a first reflective layer and a material layer to be processed on the substrate, wherein the material layer to be processed is a material layer required for preparing the intermediate layer, and the thickness of the material layer to be processed is the maximum value of the thickness of the multiple step portions;

[0092] A position mark is prepared on the side of the material layer to be processed away from the first reflective layer, and the photolithography pattern is aligned, exposed, and developed according to the position mark to form two parallel arranged N The middle layer of the terrace;

[0093] A second reflective layer is plated on a side of the intermediate layer away from the first reflective layer to form a filter.

[0094] Wherein, a position mark is prepared on the side of the material layer to be processed away from the first reflective layer, and the photolithography pattern is aligned, exposed, and developed according to the position mark to form two parallel arranged N The middle layer of the terrace includes:

[0095] The material layer to be processed is subjected to a first photolithography mask and development according to the position mark, and then the area to be etched is exposed, and other areas are masked by photoresist;

[0096] The sample is etched using RIE or ICP etching method, and the area exposed in the first step will be etched, and after cleaning the photoresist, a two-step morphology is formed;

[0097] Perform alignment photolithography and development based on the two-step morphology to also expose the area to be etched;

[0098] The exposed area is etched and cleaned, and the surface of the material layer to be processed has a 4-step morphology;

[0099] After two etchings in four steps, a 4-step material film layer is formed, which can be etched N times to form a maximum of 2 N The material film layer of the stepped morphology is formed to form two parallel arranged N The middle layer of the terrace.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A spectroscopic device, characterized in that: include: a grating, used for filtering a first incident light, wherein a transmittance of the grating to polarized light of a specific direction of the first incident light is greater than a transmittance to polarized light of other directions of the first incident light; The filter stacked with the grating is used to filter the second incident light, and the transmittance of the filter to at least one specific wavelength of the second incident light is greater than the transmittance to other wavelengths of the second incident light.

2. The optical splitter according to claim 1, characterized in that: The filter comprises: a first reflective layer; An intermediate layer, stacked with the first reflective layer; The second reflective layer is located at a side of the intermediate layer away from the first reflective layer, and the grating is arranged at a side of the second reflective layer away from the intermediate layer.

3. The optical splitter according to claim 2, characterized in that: The first reflective layer and / or the second reflective layer comprises a multilayer optical film, wherein the multilayer optical film is configured to be alternately stacked with a first refractive index film layer and a second refractive index film layer, and the refractive index of the first refractive index film layer is greater than the refractive index of the second refractive index film layer.

4. The optical splitter according to claim 2, characterized in that: The intermediate layer includes a plurality of stepped portions arranged in parallel, and the thicknesses of the plurality of stepped portions are not completely the same, so as to form a plurality of spectral channels.

5. The optical splitter according to claim 2, characterized in that: The thickness of the intermediate layer is set based on the application wavelength of the filter and the refractive index of the intermediate layer.

6. The optical splitter device according to claim 1, characterized in that: The grating is a one-dimensional rectangular metal grating.

7. The optical splitter according to claim 1, characterized in that: The grating period of the grating is smaller than a quarter of the applied wavelength of the filter.

8. The optical splitter device according to claim 1, characterized in that: The grating strip width of the grating is one tenth to nine tenths of the grating period of the grating.

9. A method for preparing a spectroscopic device, characterized in that: include: Plating a filter on the substrate, wherein the filter is used to filter the second incident light, and the transmittance of the filter to at least one specific wavelength of the second incident light is greater than the transmittance to other wavelengths of the second incident light; A grating is plated on a side of the filter away from the substrate, wherein the grating is used to filter the first incident light, and the transmittance of the grating to polarized light of a specific direction of the first incident light is greater than the transmittance to polarized light of other directions of the first incident light.

10. The method for preparing a spectroscopic device according to claim 9, characterized in that: The method of coating a filter on a substrate comprises: Plating a first reflective layer on the substrate; An intermediate layer is plated on a side of the first reflective layer away from the substrate, wherein the intermediate layer includes a plurality of stepped portions arranged in parallel, and the thicknesses of the plurality of stepped portions are not completely the same, so as to form a plurality of spectral channels; A second reflective layer is plated on a side of each step portion away from the first reflective layer.

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