CN110632692A - Filter, preparation method thereof and spectrum detection system - Google Patents
Filter, preparation method thereof and spectrum detection system Download PDFInfo
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- CN110632692A CN110632692A CN201911083060.3A CN201911083060A CN110632692A CN 110632692 A CN110632692 A CN 110632692A CN 201911083060 A CN201911083060 A CN 201911083060A CN 110632692 A CN110632692 A CN 110632692A
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- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/002—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of materials engineered to provide properties not available in nature, e.g. metamaterials
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- G02B5/00—Optical elements other than lenses
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- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/0005—Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor
- G03F7/0007—Filters, e.g. additive colour filters; Components for display devices
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Abstract
The embodiment of the invention discloses a filter, a preparation method thereof and a spectrum detection system, wherein the filter comprises a distributed Bragg reflection cavity and a super-surface structure positioned in the distributed Bragg reflection cavity; the distributed Bragg reflection cavity comprises a top distributed Bragg reflector and a bottom distributed Bragg reflector, and the super-surface structure is positioned between the top distributed Bragg reflector and the bottom distributed Bragg reflector; the super-surface structure comprises a plurality of filtering areas, and each filtering area comprises a nano-pillar array which is periodically arranged; wherein, the plurality of filtering areas at least have the nanopillar array periods of two filtering areas which are different. By adopting the technical scheme, the distributed Bragg reflection cavity is combined with the super-surface structure, and the nano-column array period of at least two filtering areas of the super-surface structure is different, so that narrow-band transmission light can be obtained, and the filter is good in filtering effect and simple in structure.
Description
Technical Field
The embodiment of the invention relates to the technical field of filtering, in particular to a filter, a preparation method thereof and a spectrum detection system.
Background
Based on the difference of light splitting modes, the spectral imaging instrument can be divided into a dispersion light splitting type, an interference filter type and a novel light splitting technology type. The development of the light splitting element as a core element of a general spectral imaging instrument has undergone the evolution from a dispersion prism to a diffraction grating, and the development course of adopting an interferometric modulation element and an information transformation technology. The dispersive spectral imager uses grating or prism to disperse the composite color light into serial spectral lines, and then uses detector to measure the intensity of each spectral line. In contrast, the dispersion spectroscopy technology is stable in process, mature in technology, simple in principle and stable in performance, and is the most widely applied technology at present. However, the dispersion light-splitting type spectral imager has relatively complex optical path, large volume and heavy weight, and is not suitable for occasions requiring portable operation. The interference type spectral imager measures the interference intensity of all spectral line elements simultaneously and performs inverse Fourier transform on the interference pattern to obtain a target spectrogram. The interference type spectral imager has small volume, light weight, stable performance, good real-time performance and wide measurement wave band, is particularly suitable for the field of spaceflight, is one of the international research hotspots at present, but cannot directly obtain a spectrogram of a certain wave band or a certain wavelength, and has poor use flexibility.
Disclosure of Invention
In view of this, embodiments of the present invention provide a filter, a method for manufacturing the filter, and a spectrum detection system, so as to solve the technical problem that a light splitting device in the prior art cannot give consideration to both good light splitting effect and simple structure.
In a first aspect, an embodiment of the present invention provides a filter, including: the distributed Bragg reflection cavity and the super-surface structure are positioned in the distributed Bragg reflection cavity;
the distributed Bragg reflection cavity comprises a top distributed Bragg reflector and a bottom distributed Bragg reflector, and the super-surface structure is positioned between the top distributed Bragg reflector and the bottom distributed Bragg reflector;
the super-surface structure comprises a plurality of filtering areas, and each filtering area comprises a nano-pillar array which is periodically arranged; wherein, the plurality of filtering areas at least have the nanopillar array periods of two filtering areas which are different.
Optionally, the plurality of filter regions at least include a first filter region and a second filter region, and a wavelength of transmitted light of the first filter region is greater than a wavelength of transmitted light of the second filter region;
the first filtering area comprises a plurality of first nano-pillars arranged in an array, the size of each first nano-pillar is L1, and the distance between every two adjacent first nano-pillars is L2;
the second filtering area comprises a plurality of second nano-pillars arranged in an array, the size of each second nano-pillar is L3, and the distance between every two adjacent second nano-pillars is L4;
wherein L1 > L3, and/or L2 > L4.
Optionally, in the vertical direction of the super-surface structure, the thickness h of the super-surface structure and the wavelength λ of incident light of the distributed bragg reflection cavity satisfy h < λ/2.
Optionally, the transmission light bandwidth Δ λ of the filtering region satisfies Δ λ ≦ 5 nm.
Optionally, the shape of the nano-pillar includes at least one of a square pillar, a rectangular pillar, a cylinder, and an elliptic pillar.
Optionally, the top-layer distributed bragg reflector and the bottom-layer distributed bragg reflector both include a first film layer and a second film layer, which are sequentially stacked in multiple layers;
the refractive index n1 of the first film layer and the refractive index n2 of the second film layer meet n1 > n 2;
the number of film layers of the top-layer distributed Bragg reflector and the bottom-layer distributed Bragg reflector is the same, and the number N of the film layers of the top-layer distributed Bragg reflector and the refractive index N1 of the first film layer and the refractive index N2 of the second film layer satisfy N and (N1-N2) are in negative correlation.
In a second aspect, an embodiment of the present invention further provides a method for manufacturing a filter, including:
preparing a bottom distributed Bragg reflector;
preparing a super-surface structure on one side of the bottom distributed Bragg reflector; the super-surface structure comprises a plurality of filtering areas, and each filtering area comprises a nano-pillar array which is periodically arranged; wherein, the plurality of filtering areas at least have the nanopillar array periods of two filtering areas which are different;
preparing a top-layer distributed Bragg reflector at the top end of the super-surface structure; and forming a distributed Bragg reflection cavity and a super-surface structure positioned in the distributed Bragg reflection cavity, wherein the structure of the filter comprises a bottom distributed Bragg reflector, the super-surface structure and a top distributed Bragg reflector from bottom to top.
Optionally, the step of preparing the super-surface structure on one side of the bottom distributed bragg reflector includes:
preparing photoresist on one side of the bottom distributed Bragg reflector;
etching the photoresist by adopting an electron beam etching, ion beam etching or nano-imprinting technology to expose part of the bottom distributed Bragg reflector;
evaporating an optical material on the top end of the photoresist to obtain a first optical material layer positioned on the top end of the bottom distributed Bragg reflector and a second optical material layer positioned on the top end of the photoresist;
and removing the photoresist and the second optical material layer to obtain a super-surface structure positioned on one side of the bottom distributed Bragg reflector.
Optionally, the top-layer distributed bragg reflector and the bottom-layer distributed bragg reflector both include a first film layer and a second film layer, which are sequentially stacked in multiple layers;
the step of preparing the bottom distributed Bragg reflector comprises the following steps:
sequentially preparing the first film layer and the second film layer which are arranged in a multi-layer laminated manner by adopting a plasma enhanced chemical vapor deposition method;
the step of preparing a top-layer distributed Bragg reflector on the top of the super-surface structure comprises the following steps:
and sequentially preparing the first film layer and the second film layer which are arranged in a multi-layer laminated manner on the top end of the super-surface structure by adopting a plasma enhanced chemical vapor deposition method.
In a third aspect, an embodiment of the present invention further provides a spectrum detection system, including the filter according to the first aspect, and further including a light detector.
According to the filter, the preparation method thereof and the spectrum detection system provided by the embodiment of the invention, the super-surface structure is arranged in the distributed Bragg reflection cavity, the nano-column array periods of at least two filtering areas of the super-surface structure are different, and the nano-column array periods of different areas are different, so that on one hand, the filtering areas with different nano-column array periods can be ensured to change optical phase information of incident light differently, transmitted light with different wavelengths can be obtained in different filtering areas, the whole filter can be ensured to obtain transmitted light with a plurality of different wavelengths, and the filtering effect of the incident light with different wavelengths is realized; on the other hand, the nanometer-precision super-surface structure can realize the precise control of the phase delay of incident light, so that the central filtering wavelength of the filter has extremely high stability and repeatability; on the other hand, the super-surface structure adopts an optical material with low optical loss, so that the loss of incident light at the super-surface structure is small, and the super-surface structure has high transmissivity; and on the other hand, the surface structure is simple in design, and the two-dimensional plane morphological characteristics of the multiple filtering areas are particularly beneficial to further integration and systematization of the filter, so that the method paves the way for future large-scale and low-cost industrial application.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments made with reference to the following drawings:
fig. 1 is a schematic diagram of an overall structure of a filter according to an embodiment of the present invention;
fig. 2 is a schematic cross-sectional structure diagram of a filter according to an embodiment of the present invention;
fig. 3 is a schematic cross-sectional structure diagram of another filter provided in the embodiment of the present invention;
fig. 4 is a schematic cross-sectional structure diagram of another filter provided in the embodiment of the present invention;
fig. 5 is a schematic cross-sectional structure diagram of another filter provided in the embodiment of the present invention;
FIG. 6 is a schematic diagram of an analog simulation of a filter including three different nanopillar array periods according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a top-layer distributed bragg reflector according to an embodiment of the present invention;
fig. 8 is a schematic flow chart of a method for manufacturing a filter according to an embodiment of the present invention;
fig. 9 is a schematic flow chart of another method for manufacturing a filter according to an embodiment of the present invention;
fig. 10-13 are schematic diagrams of steps of preparing a super-surface structure in a method for preparing a filter according to an embodiment of the present invention;
fig. 14 is a schematic structural diagram of a spectrum detection system according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be fully described by the detailed description with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are a part of the embodiments of the present invention, not all embodiments, and all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without inventive efforts fall within the scope of the present invention.
Fig. 1 is a schematic overall structure diagram of a filter according to an embodiment of the present invention, and fig. 2 is a schematic cross-sectional structure diagram of a filter according to an embodiment of the present invention, as shown in fig. 1 and fig. 2, the filter according to an embodiment of the present invention may include a distributed bragg reflector cavity 10 and a super-surface structure 20 located in the distributed bragg reflector cavity 10;
the distributed Bragg reflection cavity 10 comprises a top distributed Bragg reflector 11 and a bottom distributed Bragg reflector 12, and the super-surface structure 20 is positioned between the top distributed Bragg reflector 11 and the bottom distributed Bragg reflector 12;
the super-surface structure 20 comprises a plurality of filtering regions, wherein each filtering region comprises a nano-pillar array 21 which is periodically arranged; wherein, the period of the nano-pillar array 21 of the plurality of filtering areas at least two filtering areas is different.
Illustratively, the dbr 10 includes a top dbr 11 and a bottom dbr 12, and the top dbr 11 and the bottom dbr 12 may have the same structure.
Specifically, both the top-layer distributed bragg reflector 11 and the bottom-layer distributed bragg reflector 12 may include a multilayer film structure, and the top-layer distributed bragg reflector 11 and the bottom-layer distributed bragg reflector 12 may be guaranteed to be high-reflectivity structures by reasonably setting a growth sequence, a number of films, a growth deviation between the films, and an optimal film pair of each film in the top-layer distributed bragg reflector 11 and the bottom-layer distributed bragg reflector 12. Meanwhile, the super-surface structure 20 is arranged between the top distributed bragg reflector 11 and the bottom distributed bragg reflector 12, and the super-surface structure 20 forms a defect layer between the top distributed bragg reflector 11 and the bottom distributed bragg reflector 12, so that the filter can achieve the effect of high reflectivity of incident light of different wave bands.
Fig. 1 and 2 illustrate the case where light is incident from the top-layer bragg reflector 11 side, and considering that incident light is normally incident on the bragg reflective cavity 10, it is assumed that ni and di are the refractive index and thickness of the ith-layer medium in the top-layer distributed bragg reflector 11, no and ns are the refractive indices of the incident-layer medium and the emergent-layer medium, respectively, the wave number k is 2 pi/λ, λ is the incident wavelength, and N is the number of layers of the top-layer distributed bragg reflector 11. According to the optical transfer matrix method, by utilizing the continuity of the electric field vector and the tangential component of the magnetic field vector and combining the transfer matrix and the admittance formula, we can obtain:
then, we can obtain the equivalent admittance Y of the multilayer dielectric film in the top-layer distributed bragg reflector 11 as C/B, and then find out the corresponding light intensity reflectivity as follows according to the fresnel formula:
R＝|(n0-Y)/(n0+Y)|2
according to the above design principle and method, we can analyze and optimize each link of design from growth sequence, number of layers, growth deviation and optimal film, so as to obtain the optimized structural parameters and optical performance of the top distributed bragg reflector 11 and the bottom distributed bragg reflector 12.
The super-surface structure 20 is located in the distributed bragg reflector cavity 10, is in a two-dimensional planar array form of a Metamaterial (metamaterials), is formed by periodically or non-periodically arranging artificial 'atoms' with sub-wavelength sizes, is much thinner than the working wavelength, and is a novel artificial structure material. For the super-surface structure 20, by freely designing the unit structure, the unit arrangement mode and the unit anisotropy, medium parameters which do not exist in nature or are difficult to realize can be obtained, so that the amplitude or the phase of incident light can be effectively controlled. In the embodiment of the present invention, the super-surface structure 20 is disposed in the distributed bragg reflector cavity 10, a film layer similar to a "defect" in the distributed bragg reflector cavity 10 is formed by the super-surface structure 20, and meanwhile, the super-surface structure 20 includes a plurality of filter regions, and the plurality of filter regions may be arranged in an array, for example, in a 5 × 5 array. Each filtering area comprises a nano-column array 21 which is periodically arranged, the nano-column arrays 21 which at least have two filtering areas in a plurality of filtering areas have different periods, the nano-column arrays 21 with different array periods adjust the optical phase information of incident light to different degrees, the filtering effects of the areas with different periods of the nano-column arrays 21 on the incident light are different, the incident light which is incident on the super-surface structure 20 is ensured to obtain the transmission light with different wavelengths after passing through different filtering areas, and the filtering effects of the filter on the incident light with different wavelengths are realized. Meanwhile, the filter provided by the embodiment of the invention only comprises the distributed Bragg reflection cavity 10 and the super-surface structure 20 positioned in the distributed Bragg reflection cavity 10, and the filter has a simple structure.
To sum up, in the filter provided in the embodiment of the present invention, the super-surface structure is disposed in the distributed bragg reflection cavity, and the nano-pillar array periods of at least two filtering regions of the super-surface structure are different, and the nano-pillar array periods of different regions are different, so that on one hand, different filtering regions with different nano-pillar array periods can change optical phase information of incident light differently, transmitted light with different wavelengths can be obtained in different filtering regions, and the whole filter can obtain transmitted light with multiple different wavelengths, thereby achieving a filtering effect on incident light with different wavelengths; on the other hand, the nanometer-precision super-surface structure can realize the precise control of the phase delay of incident light, so that the central filtering wavelength of the filter has extremely high stability and repeatability; on the other hand, the super-surface structure adopts an optical material with low optical loss, so that the loss of incident light at the super-surface structure is small, and the incident light has higher transmissivity; and on the other hand, the super-surface structure is simple in design, the two-dimensional plane morphological characteristics of a plurality of filtering areas are beneficial to further systematic integration of the filter, and the road is paved for future large-scale and low-cost industrial application.
It is understood that the number of the filter regions is different in the period of the nanopillar array 21 in which at least two filter regions exist, the difference in the period of the nanopillar array 21 may be the difference in the size of the nanopillars 211 in the nanopillar array 21, and/or the difference in the period of the nanopillars 211 (the distance between two adjacent nanopillars 211), which will be described in detail below.
Fig. 3 is a schematic cross-sectional structure diagram of another filter according to an embodiment of the present invention, and fig. 3 illustrates an example in which the size of the nano-pillars 211 is different and the period of the nano-pillars 211 is the same. As shown in fig. 3, the plurality of filter regions may include at least a first filter region and a second filter region, and a wavelength of transmitted light of the first filter region is greater than a wavelength of transmitted light of the second filter region;
the first filtering region comprises first nano-pillar arrays 21a which are periodically arranged, each first nano-pillar array 21a comprises a plurality of first nano-pillars 211a, the size of each first nano-pillar 211a is L1, and the distance between every two adjacent first nano-pillars 211a is L2;
the second filtering region comprises second nano-pillar arrays 21b which are periodically arranged, each second nano-pillar array 21b comprises a plurality of second nano-pillars 211b, the size of each second nano-pillar 211b is L3, and the distance between every two adjacent second nano-pillars 211b is L4;
wherein, L1 is more than L3, and L2 is L4.
Illustratively, by setting the size of the first nanopillar 211a to be larger than the size of the second nanopillar 211b, and meanwhile, the distance between two adjacent first nanopillars 211a is the same as the distance between two adjacent second nanopillars 211b, it is ensured that the array period of the first nanopillar 211a in the first nanopillar array 21a is smaller than the array period of the second nanopillar 211b in the second nanopillar array 21b, and it is ensured that the wavelength of the transmitted light of the first nanopillar array 21a is larger than the wavelength of the transmitted light of the second nanopillar array 21b, so that different filtering effects of different filtering regions of the super-surface structure 20 on incident light are achieved, and transmitted light with different wavelengths is obtained.
Fig. 4 is a schematic cross-sectional structure diagram of another filter according to an embodiment of the present invention, and fig. 4 illustrates the nano-pillars 211 having the same size and the nano-pillars 211 having different periods. As shown in fig. 4, the plurality of filter regions may include at least a first filter region and a second filter region, and a wavelength of transmitted light of the first filter region is greater than a wavelength of transmitted light of the second filter region;
the first filtering region comprises first nano-pillar arrays 21a which are periodically arranged, each first nano-pillar array 21a comprises a plurality of first nano-pillars 211a, the size of each first nano-pillar 211a is L1, and the distance between every two adjacent first nano-pillars 211a is L2;
the second filtering region comprises second nano-pillar arrays 21b which are periodically arranged, each second nano-pillar array 21b comprises a plurality of second nano-pillars 211b, the size of each second nano-pillar 211b is L3, and the distance between every two adjacent second nano-pillars 211b is L4;
wherein, L1 is L3, and L2 is more than L4.
Illustratively, by setting the size of the first nanorod 211a to be the same as the size of the second nanorod 211b, and setting the distance between two adjacent first nanorods 211a to be greater than the distance between two adjacent second nanorods 211b, it is ensured that the array period of the first nanorod 211a in the first nanorod array 21a is smaller than the array period of the second nanorod 211b in the second nanorod array 21b, and it is ensured that the wavelength of the transmitted light of the first nanorod array 21a is greater than that of the transmitted light of the second nanorod array 21b, so that different filtering effects of different filtering regions of the super-surface structure 20 on incident light are achieved, and light with different wavelengths is obtained.
Fig. 5 is a schematic cross-sectional structure diagram of another filter according to an embodiment of the present invention, and fig. 5 illustrates an example in which the size of the nano-pillars 211 is different and the period of the nano-pillars 211 is different. As shown in fig. 5, the plurality of filter regions may include at least a first filter region and a second filter region, and a wavelength of transmitted light of the first filter region is greater than a wavelength of transmitted light of the second filter region;
the first filtering region comprises first nano-pillar arrays 21a which are periodically arranged, each first nano-pillar array 21a comprises a plurality of first nano-pillars 211a, the size of each first nano-pillar 211a is L1, and the distance between every two adjacent first nano-pillars 211a is L2;
the second filtering region comprises second nano-pillar arrays 21b which are periodically arranged, each second nano-pillar array 21b comprises a plurality of second nano-pillars 211b, the size of each second nano-pillar 211b is L3, and the distance between every two adjacent second nano-pillars 211b is L4;
wherein, L1 is more than L3, and L2 is more than L4.
Illustratively, by setting the size of the first nanopillar 211a to be larger than the size of the second nanopillar 211b, and setting the distance between two adjacent first nanopillars 211a to be larger than the distance between two adjacent second nanopillars 211b, it is ensured that the array period of the first nanopillar 211a in the first nanopillar array 21a is smaller than the array period of the second nanopillar 211b in the second nanopillar array 21b, and it is ensured that the wavelength of the transmitted light of the first nanopillar array 21a is larger than the wavelength of the transmitted light of the second nanopillar array 21b, so that different filtering effects of different filtering regions 21 of the super-surface structure 20 on incident light are achieved, and transmitted light with different wavelengths is obtained.
In conclusion, the number of the filtering areas is at least two, the period of the nano-pillar array 21 is different, the filtering areas with different periods of the nano-pillar array change the optical phase information of the transmission light differently, the transmission light with different wavelengths can be obtained in different filtering areas, the transmission light with different wavelengths can be obtained in the whole filter, the filtering effect of the incident light with different wavelengths is achieved, and the good filtering effect and the simple structure of the filter are guaranteed.
It should be noted that fig. 3, fig. 4, and fig. 5 only illustrate that the multiple filtering regions include the first filtering region and the second filtering region, and it can be understood that the super-surface structure 20 may include three or more filtering regions with different cycles of the nanopillar array 21, and the different filtering regions may ensure different changes of the optical phase information of the incident light through different cycles of the nanopillar array, ensure that the transmitted light with different wavelengths may be obtained in different filtering regions, ensure that the entire filter may obtain the transmitted light with multiple different wavelengths, and achieve a filtering effect on the incident light with different wavelengths.
Fig. 6 is a schematic diagram of an analog simulation of a filter including three different nanorod array periods according to an embodiment of the present invention, in fig. 6, the size of the nanorods 211 in different nanorod arrays 21 is set to be different, and the distance between two adjacent nanorods 211 is the same. Specifically, curve 1 shows that the size of the nanopillar 211 is 50nm by 50nm, curve 2 shows that the size of the nanopillar 211 is 30nm by 30nm, and curve 3 shows that the size of the nanopillar 211 is 10nm by 10 nm. As shown in fig. 6, in the filter region where the size of the nanopillar 211 is large, that is, the period of the nanopillar array 21 is small, the wavelength of incident light of the filter region is long. The filter provided by the embodiment of the invention can obtain a plurality of transmitted lights with different wavelengths, and realizes the light splitting and filtering effect on the incident light.
With continued reference to fig. 2, the thickness h of the super-surface structure 20 and the wavelength λ of the incident light incident to the distributed bragg reflector cavity 10 satisfy h < λ/2 along the vertical direction of the super-surface structure 20.
Illustratively, the thickness h of the super-surface structure 20 is reasonably set, for example, the thickness h of the super-surface structure 20 and the wavelength λ of incident light of the distributed bragg reflector cavity 10 are set to satisfy h < λ/2, and it is ensured that the thickness of the super-surface structure 20 is much smaller than the wavelength of the incident light, and it can be ensured that effective control and modulation on the phase delay of the incident light can be realized on a nanometer scale, so that gradual change or quasi-continuous filtering behavior can be realized in a certain waveband range.
When the incident light includes a plurality of different wavelength components, the thickness h of the super-surface structure 20 is equal to the wavelength λ of the light with the minimum wavelengthminSatisfies h < lambdamin/2. For example, when the incident light is white light, the thickness h of the super-surface structure 20 and the wavelength λ of violet light satisfy h < λ/2.
Optionally, the transmission light bandwidth Δ λ of different filter regions satisfies Δ λ ≦ 5 nm.
Illustratively, by arranging the filter to include the distributed bragg reflection cavity 10 and the super-surface structure 20 located in the distributed bragg reflection cavity 10, and reasonably setting the thickness of the super-surface structure 20 and the period of the nanorod arrays 21 in different filtering regions, it is ensured that the bandwidth of the transmitted light in different filtering regions is small, for example, the bandwidth Δ λ of the transmitted light satisfies that Δ λ is less than or equal to 5nm, and it is ensured that the filter can implement ultra-narrow band filtering.
Optionally, the shape of the nano-pillar 211 provided in the embodiment of the present invention may include at least one of a square pillar, a rectangular pillar, a cylinder, and an elliptic pillar, which is not limited in the embodiment of the present invention, and fig. 1 to 5 only illustrate that the shape of the nano-pillar 211 is a rectangular pillar.
Optionally, fig. 7 is a schematic structural diagram of a top-layer distributed bragg reflector according to an embodiment of the present invention, and as shown in fig. 7, the top-layer distributed bragg reflector 11 may include a first film layer 111 and a second film layer 112, which are stacked in sequence;
the refractive index n1 of the first film layer 111 and the refractive index n2 of the second film layer 112 satisfy n1 > n 2;
the number N of the film layers of the top-layer distributed Bragg reflector 11 is in negative correlation with the refractive index N1 of the first film layer and the refractive index N2 of the second film layer, wherein N is (N1-N2).
For example, the top-layer distributed bragg reflector 11 includes a first film 111 and a second film 112 that are sequentially stacked, where the first film 111 is a high-refractive-index film, and the second film 112 is a low-refractive-index film; in addition, the number N of the film layers of the top-layer dbr 11, the refractive index N1 of the first film layer, and the refractive index N2 of the second film layer satisfy N and (N1-N2) negative correlation, that is, when the refractive index difference between the refractive index N1 of the first film layer 111 and the refractive index N2 of the second film layer 112 is large, the number N of the film layers of the top-layer dbr 11 is small, and when the refractive index difference between the refractive index N1 of the first film layer 111 and the refractive index N1 of the second film layer 112 is small, the number N of the film layers of the top dbr 11 is large, so that the top dbr 11 can achieve high reflectivities of different wavelength. Specifically, according to actual needs, TiO2 can be selected as a high-refractive-index material and SiO2 can be selected as a low-refractive-index material pair respectively to achieve high reflectivity of different wave bands. The refractive indexes of TiO2 and SiO2 are about 2.6 and 1.45 respectively in the visible light band, and the number of the film layers of the top-layer distributed bragg reflector 11 is about 50, so that the top-layer distributed bragg reflector 11 can provide a high reflectivity band with a bandwidth of about 200nm in the visible light band.
Further, the structure of the bottom dbr 12 may be the same as the structure of the top dbr 11, and will not be described herein.
Based on the same inventive concept, an embodiment of the present invention further provides a method for manufacturing a filter, as shown in fig. 8, the method for manufacturing a filter according to the embodiment of the present invention may include:
and S110, preparing a bottom distributed Bragg reflector.
For example, the bottom distributed bragg reflector may include a plurality of first film layers and a plurality of second film layers sequentially stacked; preparing the underlying distributed bragg reflector may include:
and sequentially preparing the first film layer and the second film layer which are arranged in a multi-layer laminated manner by adopting a plasma enhanced chemical vapor deposition method to obtain the bottom-layer distributed Bragg reflector.
S120, preparing a super-surface structure on one side of the bottom distributed Bragg reflector; the super-surface structure comprises a plurality of filtering areas, and each filtering area comprises a nano-pillar array which is periodically arranged; wherein, the plurality of filtering areas at least have the nanopillar array periods of two filtering areas which are different.
For example, the super-surface structure is prepared on one side of the bottom-layer distributed bragg reflector, the super-surface structure with a plurality of filtering regions may be directly prepared on the bottom-layer distributed bragg reflector, or the prepared super-surface structure may be directly attached to the bottom-layer distributed bragg reflector.
S130, preparing a top-layer distributed Bragg reflector at the top end of the super-surface structure; and forming a distributed Bragg reflection cavity and a super-surface structure positioned in the distributed Bragg reflection cavity, wherein the structure of the filter comprises a bottom distributed Bragg reflector, the super-surface structure and a top distributed Bragg reflector from bottom to top.
For example, the top-layer distributed bragg reflector prepared on the top end of the super-surface structure may be directly prepared on the super-surface structure, or the prepared top-layer distributed bragg reflector may be directly attached to the super-surface structure.
Further, the top distributed bragg reflector may include a plurality of first film layers and a plurality of second film layers sequentially stacked; the top-layer distributed Bragg reflector prepared at the top end of the super-surface structure can be sequentially prepared into a first film layer and a second film layer which are arranged in a multi-layer laminated mode by adopting a plasma enhanced chemical vapor deposition method.
To sum up, the filter provided by the embodiment of the present invention, by preparing the bottom distributed bragg reflector, the super-surface structure and the top distributed bragg reflector, and simultaneously preparing the super-surface structure with at least two different cycles of the nano-pillar array in the filtering regions, and by setting different cycles of the nano-pillar array in different regions, on one hand, it can be ensured that the filtering regions with different cycles of the nano-pillar array change optical phase information of incident light differently, it is ensured that transmitted light with different wavelengths can be obtained in different filtering regions, it is ensured that the whole filter can obtain transmitted light with a plurality of different wavelengths, and a filtering effect on incident light with different wavelengths is achieved; on the other hand, the nanometer-precision super-surface structure can realize the precise control of the phase delay of incident light, so that the central filtering wavelength of the filter has extremely high stability and repeatability; on the other hand, the super-surface structure adopts an optical material with low optical loss, so that the loss of incident light at the super-surface structure is small, and the super-surface structure has high transmissivity; and on the other hand, the surface structure is simple in design, and the two-dimensional plane morphological characteristics of the multiple filtering areas are particularly beneficial to further integration and systematization of the filter, so that the method paves the way for future large-scale and low-cost industrial application.
It should be noted that, in the preparation method of the filter provided in the embodiment of the present invention, the order of S110, S120, and S130 is not limited, and only the preparation of the bottom-layer distributed bragg reflector, the super-surface structure, and the top-layer distributed bragg reflector in sequence is taken as an example for description. Optionally, the top-layer distributed bragg reflector is prepared first, then the super-surface structure is prepared, and finally the bottom-layer distributed bragg reflector is prepared; or, because the bottom-layer distributed bragg reflector and the top-layer distributed bragg reflector may have the same structure, the bottom-layer distributed bragg reflector and the top-layer distributed bragg reflector may also be simultaneously prepared, and then the super-surface structure is prepared, and the super-surface structure including the plurality of filtering regions is disposed between the bottom-layer distributed bragg reflector and the top-layer distributed bragg reflector.
Fig. 9 is a schematic flow chart of another method for manufacturing a filter according to an embodiment of the present invention, and how to manufacture a super-surface structure is described in detail in this embodiment. As shown in fig. 9, the preparation method provided by the embodiment of the present invention includes:
s210, preparing a bottom distributed Bragg reflector.
S220, preparing photoresist on one side of the bottom distributed Bragg reflector.
As shown in fig. 10, a photoresist 30 is prepared on the side of the bottom distributed bragg reflector 12.
And S230, etching the photoresist by adopting an electron beam etching, ion beam etching or nano-imprinting technology to expose part of the bottom distributed Bragg reflector.
As shown in fig. 11, the photoresist 30 is etched using electron beam etching, ion beam etching or nano-imprint technique to expose a portion of the underlying dbr 12. As shown in fig. 11, a plurality of preparation spaces for nano-pillars are formed on the surface of the underlying distributed bragg reflector 12 by etching the photoresist 30.
S240, evaporating an optical material on the top end of the photoresist to obtain a first optical material layer located on one side of the bottom distributed Bragg reflector and a second optical material layer located on the top end of the photoresist.
As shown in fig. 12, an optical material is deposited on the top of the photoresist 30 to obtain a first optical material layer located on one side of the bottom dbr 12 and a second optical material layer located on the top of the photoresist 30. The first optical material layer on one side of the bottom distributed bragg reflector 12 is a super-surface structure including a plurality of filtering regions.
And S250, removing the photoresist and the second optical material layer to obtain a super-surface structure positioned on one side of the bottom distributed Bragg reflector.
As shown in fig. 13, the photoresist 30 and the second optical material layer are removed to obtain the super-surface structure 20 located on one side of the bottom-layer distributed bragg reflector 12, where the super-surface structure 20 includes a plurality of filter regions, and at least two of the filter regions have different periods of the nanopillar array 21.
S260, preparing a top-layer distributed Bragg reflector at the top end of the super-surface structure; and forming a distributed Bragg reflection cavity and a super-surface structure positioned in the distributed Bragg reflection cavity, wherein the structure of the filter comprises a bottom distributed Bragg reflector, the super-surface structure and a top distributed Bragg reflector from bottom to top.
In summary, the super-surface structure is obtained by depositing a photoresist, etching the photoresist, evaporating an optical material, removing the optical colla corii asini and the optical material on the surface of the photoresist, the super-surface structure comprises a plurality of filtering areas, each filtering area comprises a nano-pillar array, and the optical phase of incident light is adjusted by the nano-pillars with different array periods, so that gradual change or quasi-continuous filtering behavior is realized in a certain waveband range, transmitted light with different wavelengths can be obtained in different filtering areas, the whole filter can obtain transmitted light with a plurality of different wavelengths, the filtering effect of the incident light with different wavelengths is realized, and the good filtering effect of the filter is ensured.
Based on the same inventive concept, an embodiment of the present invention further provides a spectrum detection system, as shown in fig. 14, fig. 14 is a schematic structural diagram of the spectrum detection system provided in the embodiment of the present invention, as shown in fig. 14, the spectrum detection system provided in the embodiment of the present invention may include the filter 100 provided in the embodiment of the present invention, and may further include the optical detector 200, where the incident light with an ultra-narrow bandwidth generated by the filter 100 is incident to some samples to be detected, and the optical detector 200 receives the transmitted light passing through the samples to be detected, and may detect characteristics of the samples to be detected, and there is a potential application in medical diagnosis and cosmetics markets.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A filter, comprising: the distributed Bragg reflection cavity and the super-surface structure are positioned in the distributed Bragg reflection cavity;
the distributed Bragg reflection cavity comprises a top distributed Bragg reflector and a bottom distributed Bragg reflector, and the super-surface structure is positioned between the top distributed Bragg reflector and the bottom distributed Bragg reflector;
the super-surface structure comprises a plurality of filtering areas, and each filtering area comprises a nano-pillar array which is periodically arranged; wherein, the plurality of filtering areas at least have the nanopillar array periods of two filtering areas which are different.
2. The filter of claim 1, wherein the plurality of filter regions comprises at least a first filter region and a second filter region, wherein a wavelength of light transmitted by the first filter region is greater than a wavelength of light transmitted by the second filter region;
the first filtering area comprises a plurality of first nano-pillars arranged in an array, the size of each first nano-pillar is L1, and the distance between every two adjacent first nano-pillars is L2;
the second filtering area comprises a plurality of second nano-pillars arranged in an array, the size of each second nano-pillar is L3, and the distance between every two adjacent second nano-pillars is L4;
wherein L1 > L3, and/or L2 > L4.
3. The filter of claim 1, wherein a thickness h of the super-surface structure and an incident light wavelength λ of the distributed bragg reflector cavity satisfy h < λ/2 in a vertical direction of the super-surface structure.
4. The filter of claim 1, wherein the transmission bandwidth Δ λ of the filtering region satisfies Δ λ ≦ 5 nm.
5. The filter of claim 1, wherein the shape of the nanopillars comprises at least one of a square pillar, a rectangular pillar, a cylinder, and an elliptical pillar.
6. The filter of claim 1, wherein the top distributed Bragg reflector and the bottom distributed Bragg reflector each comprise a plurality of first film layers and second film layers arranged in a stacked sequence;
the refractive index n1 of the first film layer and the refractive index n2 of the second film layer meet n1 > n 2;
the number of film layers of the top-layer distributed Bragg reflector and the bottom-layer distributed Bragg reflector is the same, and the number N of the film layers of the top-layer distributed Bragg reflector and the refractive index N1 of the first film layer and the refractive index N2 of the second film layer satisfy N and (N1-N2) are in negative correlation.
7. A method of making a filter, comprising:
preparing a bottom distributed Bragg reflector;
preparing a super-surface structure on one side of the bottom distributed Bragg reflector; the super-surface structure comprises a plurality of filtering areas, and each filtering area comprises a nano-pillar array which is periodically arranged; wherein, the plurality of filtering areas at least have the nanopillar array periods of two filtering areas which are different;
preparing a top-layer distributed Bragg reflector at the top end of the super-surface structure; and forming a distributed Bragg reflection cavity and a super-surface structure positioned in the distributed Bragg reflection cavity, wherein the structure of the filter comprises a bottom distributed Bragg reflector, the super-surface structure and a top distributed Bragg reflector from bottom to top.
8. The method according to claim 7, wherein the step of preparing the super-surface structure on the side of the bottom distributed Bragg reflector comprises:
preparing photoresist on one side of the bottom distributed Bragg reflector;
etching the photoresist by adopting an electron beam etching, ion beam etching or nano-imprinting technology to expose part of the bottom distributed Bragg reflector;
evaporating an optical material on the top end of the photoresist to obtain a first optical material layer positioned on the top end of the bottom distributed Bragg reflector and a second optical material layer positioned on the top end of the photoresist;
and removing the photoresist and the second optical material layer to obtain a super-surface structure positioned on one side of the bottom distributed Bragg reflector.
9. The manufacturing method according to claim 7, wherein the top distributed Bragg reflector and the bottom distributed Bragg reflector each comprise a plurality of first film layers and a plurality of second film layers which are sequentially stacked;
the step of preparing the bottom distributed Bragg reflector comprises the following steps:
sequentially preparing the first film layer and the second film layer which are arranged in a multi-layer laminated manner by adopting a plasma enhanced chemical vapor deposition method;
the step of preparing a top-layer distributed Bragg reflector on the top of the super-surface structure comprises the following steps:
and sequentially preparing the first film layer and the second film layer which are arranged in a multi-layer laminated manner on the top end of the super-surface structure by adopting a plasma enhanced chemical vapor deposition method.
10. A spectroscopic detection system comprising the filter of any one of claims 1 to 6 and further comprising a photodetector.
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