Filtering micro-nano structure and filter array

Abstract

The invention discloses a filtering micro-nano structure and a filter array, and relates to the technical field of low-illumination color imaging. The filtering micro-nano structure comprises a first micro-nano modulation layer used for being arranged on a transparent substrate of the filter, and the material of the first micro-nano modulation layer is one of a transparent material and an optical loss material; the second micro-nano modulation layer is arranged on the side, away from the transparent substrate, of the first micro-nano modulation layer, and the second micro-nano modulation layer is made of the other one of the transparent material and the optical loss material; the transparent protection layer covers the first micro-nano modulation layer and the second micro-nano modulation layer and is connected with the transparent substrate; wherein the refractive index of the transparent material is higher than that of materials of the transparent substrate and the transparent protective layer. The broadband filter can be used for broadband filtering of color imaging under small-size pixels, and meanwhile, the transmittance of incident light is improved, so that a color imaging function under low illumination is realized.

Description

Technical Field

[0001] The present application relates to the field of imaging technology, and in particular to a light filtering micro-nano structure and a filter array. Background Art

[0002] In the related art, a color image sensor is formed by adding a dye-type three-primary color filter before the photosensitive unit array to form a Bayer color filter array, which is implemented based on the mixing principle of the three primary colors.

[0003] However, when facing low-light scenes at night, the luminous flux of the Bayer color filter array is only about 1 / 3, and most of the light energy is absorbed by the dye, resulting in low energy utilization. Especially when using small-size pixel imaging devices, the imaging quality is significantly reduced, and the final image is severely distorted in color. Summary of the invention

[0004] The main purpose of the present application is to provide a light filtering micro-nano structure and a filter array, aiming to solve the technical problem of low imaging quality of the filter in the prior art when facing low-light scenes at night.

[0005] To achieve the above objectives, the present application proposes a light filtering micro-nano structure, comprising:

[0006] A first micro-nano modulation layer, the first micro-nano modulation layer is used to be disposed on a transparent substrate of the filter, and the material of the first micro-nano modulation layer is one of a transparent material and an optical loss material; the refractive index of the optical loss material is higher than the refractive index of the transparent material;

[0007] A second micro-nano modulation layer, which is disposed on a side of the first micro-nano modulation layer away from the transparent substrate, and is made of the other of a transparent material and a light loss material;

[0008] A transparent protective layer, which covers the first micro-nano modulation layer and the second micro-nano modulation layer and is connected to the transparent substrate;

[0009] The refractive index of the transparent material is higher than the refractive index of the material of the transparent substrate and the transparent protective layer.

[0010] In a possible embodiment of the present application, the transparent material is silicon nitride Si3N4 or titanium dioxide TiO2; and / or

[0011] The optical loss material is polycrystalline silicon P-Si, amorphous silicon α-Si or germanium Ge.

[0012] In a possible embodiment of the present application, the first micro-nano modulation layer and the second micro-nano modulation layer are both constructed as columnar structures, and the cross-sectional shapes of the first micro-nano modulation layer and the second micro-nano modulation layer are both rotationally symmetrical figures with a rotation angle of 90°.

[0013] In a possible embodiment of the present application, the thickness of the transparent substrate is H1, where H1>3.5 μm.

[0014] In a possible embodiment of the present application, the overall duty cycle of the first micro-nano modulation layer and the second micro-nano modulation layer is η, 0.2≤η≤0.8.

[0015] In a possible embodiment of the present application, in the first micro-nano modulation layer and the second micro-nano modulation layer, the thickness of the modulation layer made of the optical loss material is H2, 10nm≤H2≤100nm.

[0016] In a second aspect, the present application further provides a filter array, the filter array includes a regional array arranged corresponding to the photosensitive unit array, and the regional array includes a plurality of macro-pixel regions, the macro-pixel region includes at least one first filter, at least one second filter and at least one third filter, the first filter allows light of a first color to pass through, the second filter allows light of a second color to pass through, and the third filter allows light of a third color to pass through;

[0017] Among them, at least one of the first filter, the second filter and the third filter includes a first transparent substrate and a filtering micro-nano structure array arranged on one side of the first transparent substrate, the filtering micro-nano structure array includes a plurality of filtering micro-nano structures arranged in a rectangular array, and the filtering micro-nano structure is constructed as the filtering micro-nano structure provided in the first aspect.

[0018] In a possible embodiment of the present application, in the light filtering micro-nano structure, the thickness of the modulation layer made of transparent material is H3, H3>300mm; and in the light filtering micro-nano structure array, the spacing between the central axes of adjacent light filtering micro-nano structures is P, 100nm≤P≤600nm.

[0019] In a possible embodiment of the present application, the third filter is configured as a visible light all-pass filter so that the light allowed to pass is white light;

[0020] The visible light all-pass filter comprises a second transparent substrate and a second transparent protective layer, wherein the second transparent protective layer is arranged on a side of the second transparent substrate away from the photosensitive unit array.

[0021] In a possible embodiment of the present application, the macro pixel area includes 1 first filter, 1 second filter and 2 third filters, and the 1 first filter, 1 second filter and 2 third filters are arranged in a 2×2 array;

[0022] Wherein, the first filter and the second filter have the light filtering micro-nano structure provided by the first aspect.

[0023] In a possible embodiment of the present application, the side length of the first transparent substrate is e, and e satisfies: e≤3um;

[0024] Among them, in the first filter, the cross-sectional width of the first micro-nano modulation layer and the second micro-nano modulation layer is D1, D1 satisfies: 100<D1<140nm, and the spacing between the central axes of adjacent filtering micro-nano structures is P1, P1 satisfies 200<P1<300nm; in the second filter, the cross-sectional width of the first micro-nano modulation layer and the second micro-nano modulation layer is D2, 160<D2<200nm, and the spacing between the central axes of adjacent filtering micro-nano structures is P2, 350nm<P2<450nm.

[0025] In a possible embodiment of the present application, in a first diagonal direction of the macro pixel area, at least one first filter and at least one second filter are alternately arranged in sequence;

[0026] At least two third filters are arranged in sequence in a second diagonal direction of the macro pixel area;

[0027] The first diagonal direction and the second diagonal direction are parallel to each other or perpendicular to each other.

[0028] The filtering micro-nano structure provided by the technical solution of the present application constructs a double-layer modulation structure in the protective layer and the transparent substrate, and the single-layer modulation layer in the double-layer modulation structure is made of light loss material and transparent material respectively, so that the finally formed filtering micro-nano structure has the advantages of high transmittance and high modulation of the above two materials at the same time, which not only improves the transmittance of the incident light, but also ensures that the filtering micro-nano structure still has a strong broadband spectral modulation capability for reconstructing colors under the small-size pixel arrangement of several wavelengths, thereby realizing color imaging function under low illumination. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0030] Figure 1 This is a schematic structural diagram of an embodiment of the light filtering micro-nano structure of the present application;

[0031] Figure 2 A schematic cross-sectional view of a second micro-nano modulation layer of an embodiment of the light filtering micro-nano structure of the present application;

[0032] Figure 3 A schematic cross-sectional view of a second micro-nano modulation layer of another embodiment of the light filtering micro-nano structure of the present application;

[0033] Figure 4 This is a structural schematic diagram of another embodiment of the light filtering micro-nano structure of the present application;

[0034] Figure 5 A schematic diagram of filter arrangement of an embodiment of a filter array of the present application;

[0035] Figure 6 A schematic diagram of a light filtering micro-nanostructure array of a filter in the filter array of the present application;

[0036] Figure 7 Schematic diagram of high transmittance broadband modulation curves of Example 1 and Example 2;

[0037] Figure 8 A schematic diagram of a color image reconstructed using two high-transmittance broadband modulation curves of Example 1 and Example 2;

[0038] Fig. 9 A schematic diagram of high transmittance broadband modulation curves of Examples 3 and 4;

[0039] Fig.10 Schematic diagram of high-transmittance broadband modulation curves of Examples 5 and 6.

[0040] Description of Figure Numbers:

[0041] Label name Label name 10 Transparent substrate 20 Light filtering micro-nanostructure 21 The first micro-nano modulation layer 22 The second micro-nano modulation layer 23 Transparent protective layer 100 First filter 200 Second filter 300 The third filter

[0042] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0044] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0045] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0046] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0047] In the related art, a color image sensor is formed by adding a dye-type three-primary color filter before the photosensitive unit array to form a Bayer color filter array, which is implemented based on the mixing principle of the three primary colors.

[0048] However, the luminous flux of the Bayer color filter array is only about 1 / 3, and most of the light energy is absorbed by the dye of the filter, resulting in low energy utilization. In the face of low-light scenes at night, especially when used in small-size pixel imaging devices, the image quality is particularly degraded and the color distortion is serious.

[0049] To this end, the present application provides a solution, by designing the filtering micro-nano structure into a double-layer modulation structure composed of modulation layers made of light loss material and transparent material respectively, so that the double-layer modulation structure has both the high transmittance and high modulation characteristics of the light loss material and the transparent material, which not only improves the transmittance of the incident light, but also ensures that the filtering micro-nano structure still has a strong broadband spectral modulation capability under a small-size pixel arrangement of several wavelengths, thereby realizing color imaging function under low illumination, and still has a strong color reconstruction capability under a small-size pixel.

[0050] The inventive concept of the present application is further described below in conjunction with some specific embodiments.

[0051] This embodiment provides a light filtering micro-nano structure 20. The light filtering micro-nano structure 20 is formed on a surface of the filter that is away from the photosensitive unit array, and is used to filter and modulate the incident light.

[0052] In this embodiment, the light filtering micro-nano structure 20 includes a first micro-nano modulation layer 21 , a second micro-nano modulation layer 22 and a transparent protective layer 23 .

[0053] The first micro-nano modulation layer 21 is disposed on the transparent substrate 10 of the filter, and the material of the first micro-nano modulation layer 21 is one of a transparent material and an optical loss material; wherein the refractive index of the optical loss material is higher than the refractive index of the transparent material; the second micro-nano modulation layer 22 is disposed on the side of the first micro-nano modulation layer 21 away from the transparent substrate 10, and the material of the second micro-nano modulation layer 22 is the other of the transparent material and the optical loss material; the transparent protective layer 23 covers the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22, and is connected to the transparent substrate 10. The refractive index of the transparent material is higher than the refractive index of the material of the transparent substrate 10 and the transparent protective layer 23.

[0054] Specifically, see Figure 1 The transparent substrate 10 is the main part of the filter, which is made of a transparent material corresponding to the optical band, wherein the refractive index of the material of the transparent substrate is c, c satisfies: 1.4<c<2, such as various glass materials or silicon dioxide SiO2 used for filters. It can be understood that the transparent substrate 10 allows all light in the visible light band to pass through. The transparent substrate 10 and the photosensitive unit array are arranged relative to each other so that the optical signal after filtering and modulation by the filter is received by the corresponding photosensitive unit array to output a detection signal. A first micro-nano modulation layer 21 is provided on the side surface of the transparent substrate 10 facing away from the photosensitive unit array, and a second micro-nano modulation layer 22 is provided on the side surface of the first micro-nano modulation layer 21 facing away from the transparent substrate 10.

[0055] Among them, the first micro-nano modulation layer 21 has a first orthographic projection on the transparent substrate 10, and the second micro-nano modulation layer 22 has a second orthographic projection on the transparent substrate 10, and the first orthographic projection and the second orthographic projection coincide with each other, that is, in this embodiment, the outer peripheral surfaces of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are coplanar and perpendicular to the transparent substrate 10, so as to facilitate the incident light to pass through the double-layer modulation structure and enter the transparent substrate 10.

[0056] It is worth mentioning that the material of the first micro-nano modulation layer 21 is one of a transparent material and an optical loss material, and the material of the second micro-nano modulation layer 22 is the other of a transparent material and an optical loss material. That is, when the material of the first micro-nano modulation layer 21 is a transparent material, the material of the second micro-nano modulation layer 22 is an optical loss material. Alternatively, when the material of the second micro-nano modulation layer 22 is a transparent material, the material of the first micro-nano modulation layer 21 is an optical loss material. It can be understood that in this embodiment, the high refractive index and low refractive index of the material are for the visible light band. Specifically, the refractive index of the transparent material is a, and a satisfies: 2<a<3. At this time, the transparent material is a low refractive index transparent material in the visible light band, and the refractive index of the optical loss material is b, and b satisfies: 3<b<5. At this time, the optical loss material is a high refractive index optical loss material in the visible light band.

[0057] The transparent protective layer 23 is arranged on the side of the transparent substrate 10 away from the photosensitive unit array, and is coated on the outside of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22. Optionally, the protective layer 23 is formed by a photoresist filled around the micro-nano structure, which is used to protect the micro-nano structure and to flatten the filter surface, facilitating the preparation of other structural devices such as microlenses thereon. Among them, the refractive index of the material of the transparent protective layer 23 is d, and d satisfies: 1.4<d<2. In this way, the refractive index of the transparent material used in the modulation layer is higher than the refractive index of the material of the transparent substrate 10 and the transparent protective layer 23.

[0058] In this embodiment, the modulation layer made of a light loss material with a high refractive index is used to increase the refractive index contrast between the micro-nano structure as a whole and the surrounding medium, such as the photoresist and the filter substrate, thereby improving the coupling strength between the incident light field of the micro-nano structure and the waveguide light field in the micro-nano structure, and enhancing the filtering and modulation capabilities of the micro-nano structure when the number is small. In addition, the light loss of the light loss material will reduce the quality factor Q of the resonance in the transparent substrate 10, which is conducive to the accurate reconstruction of the subsequent color after broadband modulation.

[0059] It can be understood that when light enters another medium from one medium, if the difference in refractive index between the two media decreases, the energy of the reflected light decreases and the energy of the transmitted light increases. Specifically in this embodiment, since the refractive index of the transparent material is higher than the refractive index of the transparent substrate 10 and the transparent protective layer 23, the difference in refractive index between adjacent media from the incident end to the transmission end of the light filtering micro-nano structure decreases, thereby improving the transmittance in this embodiment.

[0060] It is not difficult to see that the present embodiment designs the light filtering micro-nano structure 20 as a double-layer modulation layer structure formed by stacking modulation layers made of a light loss material with a higher refractive index and a transparent material with a lower refractive index. The double-layer modulation layer structure has both the high transmittance and high modulation characteristics of the light loss material with a higher refractive index and the transparent material with a lower refractive index. It not only improves the transmittance of the incident light, but also ensures that the light filtering micro-nano structure still has a strong broadband spectral modulation capability under a small-size pixel arrangement of several wavelengths, thereby realizing a color imaging function under low illumination, and can improve the overall broadband spectral modulation capability of the filter in the case of a decrease in spectral modulation capability caused by a decrease in refractive index contrast after a small-size pixel and a transparent protective layer 23, thereby ensuring that the filter still has a strong broadband spectral modulation capability for color reconstruction.

[0061] In addition, compared with the existing complementary color filter array, the filter micro-nano structure 20 provided in this embodiment does not need to additionally prepare a multi-layer coated filter, thereby reducing the manufacturing cost.

[0062] In a possible embodiment of the present application, the transparent material is silicon nitride Si3N4 or titanium dioxide TiO2. It can be understood that the refractive index of Si3N4 or TiO2 is higher than the refractive index of various glass materials or silicon dioxide SiO2 used for filters.

[0063] In a possible embodiment of the present application, the optical loss material is polycrystalline silicon P-Si, amorphous silicon α-Si or germanium Ge. At this time, in the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22, the thickness of the modulation layer made of the optical loss material is H2, 10nm≤H2≤100nm, which can ensure that the micro-nano structure has a large light flux, such as greater than 60%, and enhance the broadband modulation capability of the filter under a small number of micro-nano structures, thereby avoiding a decrease in broadband modulation capability.

[0064] In a possible embodiment of the present application, the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are both constructed as columnar structures, and the cross-sectional shapes of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are both rotationally symmetrical figures with a rotation angle of 90°.

[0065] Specifically, the double-layer modulation structure composed of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 is constructed as a columnar structure protruding from the transparent substrate 10. And the central axis of the columnar structure is perpendicular to the surface of the transparent substrate 10. The cross-section of any modulation layer in the double-layer modulation structure is the intersection area of ​​the plane parallel to the plane where the transparent substrate 10 is located and the modulation layer. In this embodiment, the cross-sectional shape of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are both rotationally symmetric figures with a rotation angle of 90° to ensure the polarization-independent characteristics of the spectral modulation, thereby maintaining the high transmittance of the micro-nano structure. For example, please refer to Figure 2and Figure 3 The rotationally symmetric image with a rotation angle of 90° can be a circle, a square, a ring, etc.

[0066] In a possible embodiment of the present application, please refer to Figure 1 , the thickness of the transparent substrate 10 is H1, H1>5λ. λ is the average wavelength of the visible light band, and at this time, the broadband modulation interference caused by the Fabry-Peror resonance in the transparent substrate 10 can be reduced.

[0067] In a possible embodiment of the present application, the overall duty cycle of the double-layer modulation structure composed of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 is η, 0.2≤η≤0.8, to ensure that the double-layer modulation structure is easy to etch and prepare by ICP (inductively coupled plasma) etching technology, etc. The overall duty cycle is the ratio of the cross-sectional width of the columnar structure to the total layer height of the double-layer modulation structure.

[0068] Specifically, the cross-sectional width of the columnar structure is D, then η=D / (H2+H3). Wherein, H3 is the thickness of the modulation layer made of transparent material. When the cross-sectional shape of the first micro-nano modulation layer and the second micro-nano modulation layer is circular, the cross-sectional width D is the cross-sectional diameter of the columnar structure. When the cross-sectional shape of the first micro-nano modulation layer and the second micro-nano modulation layer is square, the cross-sectional width D is the cross-sectional side length of the columnar structure.

[0069] Second, see Figure 5 The present application provides a filter array, which includes a regional array arranged corresponding to the photosensitive unit array, and the regional array includes multiple macro-pixel areas, the macro-pixel area includes at least one first filter 100, at least one second filter 200 and at least one third filter 300, the first filter 100 allows light of a first color to pass through, the second filter 200 allows light of a second color to pass through, and the third filter 300 allows light of a third color to pass through.

[0070] Among them, at least one of the first filter 100, the second filter 200 and the third filter 300 includes a first transparent substrate and a filtering micro-nano structure array arranged on one side of the first transparent substrate, the filtering micro-nano structure array includes a plurality of filtering micro-nano structures 20 arranged in a rectangular array, and the filtering micro-nano structure 20 is constructed as the filtering micro-nano structure 20 provided in the aforementioned embodiment.

[0071] The specific structure of the light filtering micro-nano structure 20 refers to the above embodiment. Since the filter array adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0072] In addition, in this embodiment, the filter array is constructed as a regional array corresponding to the photosensitive unit array. At this time, each sub-region in the regional array corresponds to a single pixel one by one. In the regional array, the sub-regions in a certain square array area are combined to form a macro-pixel area. During color reconstruction, the macro-pixel area is taken as the object, and the color of the macro-pixel area can be reconstructed according to the light energy output by the photosensitive unit corresponding to each sub-region in the macro-pixel area. Among them, the macro-pixel area includes at least 4 sub-regions arranged in a square array, that is, the macro-pixel can be a sub-region square array of 2×2, 3×3 or 4×4.

[0073] Understandable, see Figure 5 The filter array includes a transparent medium layer facing all the photosensitive units, and the transparent medium layer is divided into a plurality of block-shaped transparent substrates 10 through a sub-region array. At this time, each transparent substrate 10 forms a filter in combination with the filter structure arranged thereon.

[0074] Among them, the filtering structure can be constructed as a filtering micro-nano structure array, and each filtering micro-nano structure 20 in the filtering micro-nano structure array is constructed as the filtering micro-nano structure 20 provided in the aforementioned embodiment, or it can be an existing filtering structure. This embodiment is not limited to this, as long as the filter corresponding to at least one color has the filtering micro-nano structure 20 provided in the aforementioned embodiment.

[0075] Of course, the space on one side of the transparent substrate 10 away from the photosensitive unit may not be provided with the light filtering micro-nano structure 20, so that this part of the filter substantially allows all light in the visible light band to pass through, that is, allows white light to pass through, to form a visible light all-pass filter.

[0076] For the filter structure, which can be constructed as a filter of the filter micro-nano structure 20 provided in the above-mentioned embodiment, on a single transparent substrate 10, see Figure 6 , multiple identical light filtering micro-nano structures 20 are arranged in a rectangular array and spaced apart from each other, thereby forming a filter micro-nano structure array. At this time, the filter micro-nano structure array has a corresponding spectral modulation capability, that is, it allows light of some light bands to pass through, while the rest of the light bands are not allowed to pass through. That is, it allows light of one color to pass through.

[0077] In a possible embodiment of the present application, in the light filtering micro-nano structure 20, the thickness of the modulation layer made of transparent material is H3, H3>300mm; and in the light filtering micro-nano structure array, the spacing between the central axes of adjacent light filtering micro-nano structures 20 is P, 100nm≤P≤600nm.

[0078] The spacing P is the arrangement period of the filter micro-nanostructures in the filter micro-nanostructure array. At this time, H3>300mm combined with 100nm≤P≤600nm will reduce the interaction between spectral channels, such as resonance, so as to ensure that the filter micro-nanostructure array can provide several waveguide modes for spectral modulation.

[0079] In a possible embodiment of the present application, the third filter 300 is configured as a visible light all-pass filter so that the light allowed to pass is white light.

[0080] Specifically, the visible light all-pass filter only includes a second transparent substrate and a second transparent protective layer, and the second transparent protective layer is arranged on the side of the second transparent substrate away from the photosensitive unit array. The second transparent substrate is a transparent substrate 10 corresponding to a sub-region in the transparent medium layer.

[0081] It can be understood that there is no micro-nano structure portion space on the transparent substrate 10 corresponding to at least one sub-region in the macro-pixel region to allow all light in the visible light band to pass through. At this time, the filter set in at least one sub-region in the macro-pixel region is the third filter 300. It can be understood that the visible light all-pass filter approximates the all-pass light energy, which can further improve the overall light throughput of the filter array.

[0082] Specifically, in a possible embodiment of the present application, the macro-pixel area includes one first filter 100, one second filter 200 and two third filters 300, and one first filter 100, one second filter 200 and two third filters 300 are arranged in a 2×2 array; wherein the first filter 100 and the second filter 200 have the filtering micro-nano structure provided in the aforementioned embodiment.

[0083] At this time, the first filter 100 and the second filter 200 allow light of different colors to pass through, that is, the first filter 100 and the second filter 200 have different light filtering micro-nano structures. The two filters with different light filtering micro-nano structures are combined with two third filters to form a 2×2 array macro pixel.

[0084] In a possible embodiment of the present application, the side length of the first transparent substrate is e, and e satisfies: e≤3um. Specifically, the side length of the first transparent substrate is less than or equal to 3um, so that the filter micro-nano structure array is distributed in a 3um×3um area, that is, in this embodiment, the filter corresponds to the small-size pixel.

[0085] Preferably, in the first filter 100, the cross-sectional width of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 is D1, and D1 satisfies: 100<D1<140nm. The spacing between the central axes of adjacent light filtering micro-nano structures is P1, and P1 satisfies 200<P1<300nm.

[0086] Specifically, since the double-layer modulation structure composed of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 is a columnar structure, and the cross-sectional shape is a rotationally symmetrical figure with a rotation angle of 90°. Therefore, when the cross-sectional shape of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 in the first filter 100 is circular, the cross-sectional width D1 is the cross-sectional diameter of the columnar structure. When the cross-sectional shape of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 in the first filter 100 is square, the cross-sectional width D1 is the cross-sectional side length of the columnar structure. The spacing P1 is the arrangement period of the filter micro-nano structure in the filter micro-nano structure array.

[0087] Preferably, in the second filter 200 , the cross-sectional widths of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are D2, 160<D2<200nm, and the spacing between the central axes of adjacent filtering micro-nano structures is P2, 350nm<P2<450nm.

[0088] That is, when the cross-sectional shape of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 in the second filter 200 is circular, the cross-sectional width D2 is the cross-sectional diameter of the columnar structure. When the cross-sectional shape of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 is square, the cross-sectional width D2 is the cross-sectional side length of the columnar structure. The spacing P2 is the arrangement period of the filter micro-nano structure in the filter micro-nano structure array.

[0089] The preferred embodiment provided in this embodiment has a better combination of arrangement period and shape size parameters, which can enable the filter array to still have a broadband modulation function of accurately reconstructing colors under low illumination with small-sized pixels.

[0090] In a possible embodiment of the present application, in the first diagonal direction of the macropixel area, at least one first filter 100 and at least one second filter 200 are arranged alternately in sequence; in the second diagonal direction of the macropixel area, at least two third filters 300 are arranged in sequence.

[0091] The first diagonal direction and the second diagonal direction are parallel to each other or perpendicular to each other.

[0092] See also Figure 5For the 2×2 macro pixel area in the upper left corner of a regional array, the first filter 100 is located in the sub-area in the upper left corner, the second filter 200 is located in the sub-area in the lower right corner, and the two third filters 300 are respectively located in the sub-areas in the upper right corner and the lower left corner. At this time, the first diagonal direction is from the upper left to the lower right direction, and the second diagonal direction is from the upper right to the lower left direction, and the two are perpendicular to each other. Of course, one of the first filter 100 and the second filter 200 is preferably that both have the light filtering micro-nano structure 20 provided in the aforementioned embodiment.

[0093] In the following, both of them have the light filtering micro-nano structure 20 provided in the above embodiment, and the third filter 300 is a visible light all-pass filter. At this time, the high transmittance broadband modulation curve of the first filter 100 is M1, the high transmittance broadband modulation curve of the second filter 200 is M2, and the energy value accepted by the third filter 300 is approximately the same, which can be expressed as C. All the light filtering micro-nano structures 20 in the first filter 100 and the second filter 200 provide a total of n spectral modulation channels. At this time, the light energy values ​​I1, I2, and I3 of the three colors received by the macro pixel area are expressed as:

[0094] Equation 1:

[0095] Where A is the modulation matrix composed of broadband modulation curves M1, M2 and C, φ n is the incident spectrum of the nth spectral modulation channel. Using the compressed sensing algorithm, equation 1 can be solved to obtain the incident spectrum corresponding to the macro pixel, and the color RGB value of the incident light at the macro pixel position is as follows:

[0096]

[0097] It can be understood that the compressed sensing algorithm requires that the correlation between the high transmittance broadband modulation curve M1 and the high transmittance broadband modulation curve M2 is small, and they are as close to the linear combination of the R, G, and B curves as possible. That is, at this time, M1 and M2 satisfy: min||M i -(a·R+b·G+c·B)||2, i=1,2. Where a, b, c are constants. At the same time, the minimum normalized singular value of the modulation matrix A composed of M1, M2 and C, that is, α=min[SVD(A)] / sum[SVD(A)], should generally be greater than 0.05, where SVD(A) is the singular value decomposition (Single Value Decomposition) of the modulation matrix A.

[0098] It can be understood that the first filter 100 and the second filter 200 allow different colors of light to pass through, that is, the specific structures of the filtering micro-nanostructure arrays in the first filter 100 and the second filter 200 are different, which may specifically include at least one of the different shapes of single micro-nanostructures, different spacings between adjacent micro-nanostructures, or different numbers of micro-nanostructures.

[0099] In order to enable those skilled in the art to better understand the scope of protection of the claims of this application. The following is an explanation of the technical solutions recorded in the claims of this application through specific implementation examples. It can be understood that the following examples are only used to explain this application, and are not used to limit the scope of protection of the claims of this application. In the following examples, the combination of the structural height, arrangement period and shape and size parameters of the modulation layer is better, which can enable the filter array to still have a broadband modulation function of accurately reconstructing colors under low illumination under small-sized pixels.

[0100] Structure 1: Please refer to Figure 1 The transparent substrate 10 is made of silicon dioxide SiO2, and the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are both constructed as a columnar structure with a circular cross-section. The first micro-nano modulation layer 21 uses amorphous Si (α-Si), a light loss material, and the second micro-nano modulation layer 22 uses titanium dioxide TiO2, a transparent material. It can be understood that the refractive index of TiO2 is greater than that of SiO2.

[0101] The height of the second micro-nano modulation layer 22 is between 200-1000nm, and the spacing is between 200-500nm, so as to ensure that there are several waveguide modes for modulation in the double-layer modulation structure. In order to ensure a larger light flux and enhance the broadband modulation capability under a small number of micro-nano structures, the height of the first micro-nano modulation layer 21 is between 20-100nm. The overall duty cycle of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 is between 0.2-0.8 to ensure that the structure is easy to etch and prepare.

[0102] Based on the above structure 1, two specific examples are provided:

[0103] Example 1: The height of the first micro-nano modulation layer 21 (α-Si) is 62.8 nm, the height of the second micro-nano modulation layer 22 (TiO2) is 465.4 nm, the spacing is 265.2 nm, and the duty cycle is 0.31;

[0104] Example 2: The height of the first micro-nano modulation layer 21 (α-Si) is 62.8 nm, the height of the second micro-nano modulation layer 22 (TiO2) is 465.4 nm, the spacing is 377.3 nm, and the duty cycle is 0.57.

[0105] The first filter 100 is formed by the light filtering micro-nano structure 20 provided in Example 1, and the second filter 200 is formed by the light filtering micro-nano structure 20 provided in Example 2. In a 2×2 macro pixel area, the first filter 100 is located in the sub-area at the upper left corner, the second filter 200 is located in the sub-area at the lower right corner, and two third filters 300 that allow white light to pass are respectively located in the sub-areas at the upper right corner and the lower left corner.

[0106] See also Figure 7 , are the high transmittance broadband modulation curves of Example 1 and Example 2. It can be seen that the high transmittance broadband modulation curves of Example 1 and Example 2 reach 75.4% and 68.6% respectively. Figure 8 , Figure 8 The image on the left is the reference image, and the reference image is the true value image; Figure 8 The image on the right side of the middle is a color image reconstructed using the high-transmittance broadband modulation curves of Examples 1 and 2. The color accuracy of the color image is measured by the quantitative indicator ΔE (delta-E). The average value of the color deviation ΔE of the color image is as low as 0.87, which shows that the filter arrays of Examples 1 and 2 accurately reconstruct the image color.

[0107] Structure 2: Please refer to Figure 4 The transparent substrate 10 is made of SiO2, and the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are both constructed as a columnar structure with a circular cross section. The first micro-nano modulation layer 21 is made of a transparent material silicon nitride Si3N4, and the second micro-nano modulation layer 22 is made of a light loss material polycrystalline Si (p-Si).

[0108] The height of the first micro-nano modulation layer 21 is between 200-1500nm, and the spacing P is between 200-500nm to ensure that there are several waveguide modes for modulation in the double-layer modulation structure. In order to ensure a large light flux and modulation capability, the height of the second micro-nano modulation layer 22 is between 30-200nm. The overall duty ratio of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 is between 0.2-0.8 to ensure that the structure is easy to etch and prepare.

[0109] Based on the above structure 2, two specific examples are provided:

[0110] Example 3: The height of the first micro-nano modulation layer 21 (Si3N4) is 431.3 nm, the height of the second micro-nano modulation layer 22 (p-Si) is 76.5 nm, the spacing is 269.2 nm, and the duty cycle is 0.44;

[0111] Example 4: The height of the first micro-nano modulation layer 21 (Si3N4) is 431.3 nm, the height of the second micro-nano modulation layer 22 (p-Si) is 76.5 nm, the spacing is 347.9 nm, and the duty cycle is 0.54.

[0112] The first filter 100 is formed by the light filtering micro-nano structure 20 provided in Example 3, and the second filter 200 is formed by the light filtering micro-nano structure 20 provided in Example 4. In a 2×2 macro pixel area, the first filter 100 is located in the sub-area at the upper left corner, the second filter 200 is located in the sub-area at the lower right corner, and two third filters 300 that allow white light to pass are respectively located in the sub-areas at the upper right corner and the lower left corner.

[0113] See also Fig. 9 , which are high transmittance broadband modulation curves of Examples 3 and 4. It can be seen that the high transmittance broadband modulation curves of Examples 3 and 4 reach 65.7% and 72.7% respectively. The average value of the color deviation ΔE of the reconstructed color image is as low as 1.13, which shows that the filter arrays of Examples 3 and 4 accurately reconstruct the image color.

[0114] Structure 3: Please refer to Figure 3 The transparent substrate 10 is made of SiO2, and the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are both constructed as columnar structures with square cross-sections. The first micro-nano modulation layer 21 is made of light loss material polycrystalline Si (p-Si), and the second micro-nano modulation layer 22 is made of transparent material titanium dioxide TiO2.

[0115] The height of the first micro-nano modulation layer 21 is between 20-100nm, and the spacing P is between 200-500nm to ensure that there are several waveguide modes for modulation in the double-layer modulation structure. In order to ensure a large light flux and modulation capability, the height of the second micro-nano modulation layer 22 is between 200-1000nm. The overall duty ratio of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 is between 0.2-0.8 to ensure that the structure is easy to etch and prepare.

[0116] Based on the above structure three, two specific examples are provided:

[0117] Example 5: The height of the first micro-nano modulation layer 21 (p-Si) is 83.6 nm, the height of the second micro-nano modulation layer 22 (TiO2) is 313.2 nm, the spacing is 379.7 nm, and the duty cycle is 0.41;

[0118] Example 6: The height of the first micro-nano modulation layer 21 (p-Si) is 83.6 nm, the height of the second micro-nano modulation layer 22 (TiO2) is 313.2 nm, the spacing is 271.6 nm, and the duty cycle is 0.62.

[0119] The first filter 100 is formed by the light filtering micro-nano structure 20 provided in Example 5, and the second filter 200 is formed by the light filtering micro-nano structure 20 provided in Example 6. In a 2×2 macro pixel, the first filter 100 is located in the sub-region in the upper left corner, the second filter 200 is located in the sub-region in the lower right corner, and two third filters 300 that allow white light to pass are respectively located in the sub-regions in the upper right corner and the lower left corner.

[0120] See also Fig.10 , which are high transmittance broadband modulation curves of Examples 5 and 6. It can be seen that the high transmittance broadband modulation curves of Examples 5 and 6 reach 77.9% and 63.8% respectively. The average value of the color deviation ΔE of the reconstructed color image is as low as 1.21, which shows that the filter arrays of Examples 5 and 6 accurately reconstruct the image color.

[0121] The above description is only an optional embodiment of the present application, and does not limit the patent scope of the present application. All equivalent structural transformations made by using the contents of the present application specification and drawings under the inventive concept of the present application, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A light filtering micro-nano structure, characterized in that: include: A first micro-nano modulation layer, wherein the first micro-nano modulation layer is disposed on a transparent substrate of the filter, and a material of the first micro-nano modulation layer is one of a transparent material and an optical loss material, and a refractive index of the optical loss material is higher than a refractive index of the transparent material; A second micro-nano modulation layer, wherein the second micro-nano modulation layer is disposed on a side of the first micro-nano modulation layer away from the transparent substrate, and the material of the second micro-nano modulation layer is the other of the transparent material and the light loss material; A transparent protective layer, the transparent protective layer covers the first micro-nano modulation layer and the second micro-nano modulation layer and is connected to the transparent substrate; The refractive index of the transparent material is higher than the refractive index of the material of the transparent substrate and the transparent protective layer.

2. The light filtering micro-nano structure according to claim 1, characterized in that: The transparent material is silicon nitride Si3N4 or titanium dioxide TiO2; and / or The optical loss material is polycrystalline silicon P-Si, amorphous silicon α-Si or germanium Ge.

3. The light filtering micro-nano structure according to claim 1, characterized in that: The first micro-nano modulation layer and the second micro-nano modulation layer are both constructed as columnar structures, and the cross-sectional shapes of the first micro-nano modulation layer and the second micro-nano modulation layer are both rotationally symmetrical figures with a rotation angle of 90°.

4. The light filtering micro-nano structure according to claim 1, characterized in that: The thickness of the transparent substrate is H1, and H1>3.5 μm.

5. The light filtering micro-nano structure according to claim 1, characterized in that: The overall duty cycle of the first micro-nano modulation layer and the second micro-nano modulation layer is η, 0.2≤η≤0.

8.

6. The light filtering micro-nano structure according to claim 1, characterized in that: In the first micro-nano modulation layer and the second micro-nano modulation layer, the thickness of the modulation layer made of the optical loss material is H2, and 10nm≤H2≤100nm.

7. A filter array, characterized in that: The filter array includes a region array corresponding to the photosensitive unit array, and the region array includes a plurality of macro-pixel regions, the macro-pixel region includes at least one first filter, at least one second filter and at least one third filter, the first filter allows light of a first color to pass through, the second filter allows light of a second color to pass through, and the third filter allows light of a third color to pass through; Wherein, at least one of the first filter, the second filter and the third filter comprises a first transparent substrate and a light filtering micro-nano structure array arranged on one side of the first transparent substrate, the light filtering micro-nano structure array comprises a plurality of light filtering micro-nano structures arranged in a rectangular array, and the light filtering micro-nano structure is constructed as the light filtering micro-nano structure as described in any one of claims 1 to 6.

8. The filter array according to claim 7, characterized in that: In the light filtering micro-nano structure, the thickness of the modulation layer made of transparent material is H3, H3>300mm; and in the light filtering micro-nano structure array, the spacing between the central axes of adjacent light filtering micro-nano structures is P, 100nm≤P≤600nm.

9. The filter array according to claim 8, characterized in that: The third filter is configured as a visible light all-pass filter so that the light allowed to pass is white light; The visible light all-pass filter includes a second transparent substrate and a second transparent protective layer, wherein the second transparent protective layer is arranged on a side of the second transparent substrate away from the photosensitive unit array.

10. The filter array according to claim 9, characterized in that The macro pixel area includes one first filter, one second filter and two third filters, and one first filter, one second filter and two third filters are arranged in a 2×2 array; Wherein, both the first filter and the second filter have the light filtering micro-nano structure as described in any one of claims 1 to 6.

11. The filter array according to claim 10, characterized in that The side length of the first transparent substrate is e, and e satisfies: e≤3um; Among them, in the first filter, the cross-sectional width of the first micro-nano modulation layer and the second micro-nano modulation layer is D1, D1 satisfies: 100<D1<140nm, and the spacing between the central axes of adjacent filtering micro-nano structures is P1, P1 satisfies 200<P1<300nm; in the second filter, the cross-sectional width of the first micro-nano modulation layer and the second micro-nano modulation layer is D2, 160<D2<200nm, and the spacing between the central axes of adjacent filtering micro-nano structures is P2, 350nm<P2<450nm.

12. The filter array according to claim 9, characterized in that: In a first diagonal direction of the macro pixel area, at least one of the first filters and at least one of the second filters are alternately arranged in sequence; In the second diagonal direction of the macro pixel area, at least two of the third filters are arranged in sequence; The first diagonal direction and the second diagonal direction are parallel to each other or perpendicular to each other.

Images