Filter Micro-Nano Structure and Filter Array

Abstract

The present application discloses a light filtering micro-nano structure and a filter array, which relate to the technical field of low-illumination color imaging. The light filtering micro-nano structure includes: a first micro-nano modulation layer, which is used to be 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 a light loss material; a second micro-nano modulation layer, which is arranged on the 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 a transparent material and a light loss material; 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; wherein 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. The present application can be used for broadband filtering of color imaging under small-size pixels, while improving the transmittance of incident light, thereby realizing color imaging function under low illumination.

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, where 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 layer thickness of the modulation layer made of a light loss material is H2, where 10 nm ≤ H2 ≤ 100 nm.

[0016] In a second aspect, the present application further provides a filter array. The filter array includes a region array corresponding to the photosensitive unit array, and the region array includes a plurality of macro pixel regions. Each 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 filter micro-nano structure array disposed on one side of the first transparent substrate. The filter micro-nano structure array includes a plurality of filter micro-nano structures arranged in a rectangular array, and the filter micro-nano structures are configured as the filter micro-nano structures provided in the first aspect.

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

[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 through is white light.

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

[0021] In a possible embodiment of the present application, each macro pixel region 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] Among them, the first filter and the second filter have the filter micro-nano structures provided in 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 ≤ 3 μm.

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

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

[0026] In the second diagonal direction of the macro-pixel region, at least two third filters are arranged in sequence;

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

[0028] The filter 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. The single-layer modulation layers in the double-layer modulation structure are made of a light-loss material and a transparent material respectively, so that the finally formed filter micro-nano structure simultaneously has the advantages of high transmittance and high modulation of the foregoing two materials, not only improving the transmittance of incident light, but also ensuring that the filter micro-nano structure still has a strong broadband spectral modulation ability for reconstructing colors under the arrangement of small-size pixels at several wavelengths, and further realizing the color imaging function under low illuminance. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

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

[0031] Figure 2 It is a cross-sectional view of the second micro-nano modulation layer of an embodiment of the filter micro-nano structure of the present application;

[0032] Figure 3 It is a cross-sectional view of the second micro-nano modulation layer of another embodiment of the filter micro-nano structure of the present application;

[0033] Figure 4 Schematic diagram of another embodiment of the filter micro-nano structure of the present application;

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

[0035] Figure 6 Schematic diagram of the filter micro-nano structure array of a filter in the filter array of the present application;

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

[0037] Figure 8 Schematic diagram of the color image reconstructed using the two high transmittance broadband modulation curves of Example 1 and Example 2;

[0038] Figure 9 Schematic diagram of the high transmittance broadband modulation curves of Example 3 and Example 4;

[0039] Figure 10 Schematic diagram of the high transmittance broadband modulation curves of Example 5 and Example 6.

[0040] Explanation of the reference numerals in the drawings:

[0041] Label Name Label Name 10 Transparent substrate 20 Filtering micro-nano structure 21 First micro-nano modulation layer 22 Second micro-nano modulation layer 23 Transparent protective layer 100 First filter 200 Second filter 300 Third filter

[0042] The realization, functional features and advantages of the purpose of the present application will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0043] Next, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

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

[0045] In this application, unless otherwise clearly defined and limited, terms such as "connection" and "fixation" shall be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0046] In addition, if the descriptions such as "first" and "second" are involved in the embodiments of this application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one such feature. In addition, the meaning of "and / or" appearing throughout the text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or the solution where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions appears to be contradictory or unable to 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 forms a Bayer color filter array by adding dye-type trichromatic filters in front of a photosensitive unit array and is realized according to the mixing principle of the three primary colors.

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

[0049] For this reason, this application provides a solution. By designing the filter micro-nano structure into a double-layer modulation structure formed by laminating modulation layers made of a light-loss material and a transparent material respectively, the double-layer modulation structure simultaneously has the high transmittance and high modulation characteristics of the light-loss material and the transparent material, not only improving the transmittance of incident light, but also ensuring that the filter micro-nano structure still has a strong broadband spectral modulation ability under the arrangement of small-size pixels at several wavelengths. Furthermore, the color imaging function under low illumination can be realized, and strong color reconstruction ability can still be achieved under small pixels.

[0050] The following further elaborates on the inventive concept of this application in combination with some specific embodiments.

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

[0052] In this embodiment, the filter 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] Among them, 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 a light loss material; wherein, the refractive index of the light loss material is higher than that of the transparent material; the second micro-nano modulation layer 22 is disposed on the side of the first micro-nano modulation layer 21 facing 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 light 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 indices of the materials of the transparent substrate 10 and the transparent protective layer 23.

[0054] Specifically, please refer to 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. Among them, the refractive index of the material of the transparent substrate is c, and c satisfies: 1.4 < c < 2. Specifically, it is various glass materials or silicon dioxide SiO2, etc. used for filters. It can be understood that the transparent substrate 10 allows all light rays in the visible light band to pass through. The transparent substrate 10 and the photosensitive unit array are arranged opposite to each other so that the light signal filtered and modulated by the filter can be received by the corresponding photosensitive unit array to output a detection signal. The first micro-nano modulation layer 21 is disposed on the surface of the transparent substrate 10 on the side facing away from the photosensitive unit array, and the second micro-nano modulation layer 22 is disposed on the 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, 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 noting that the material of the first micro-nano modulation layer 21 is one of a transparent material and a light-loss material, and the material of the second micro-nano modulation layer 22 is the other of the transparent material and the light-loss material. That is, when the material of the first micro-nano modulation layer 21 is the transparent material, the material of the second micro-nano modulation layer 22 is the light-loss material. Or, when the material of the second micro-nano modulation layer 22 is the transparent material, the material of the first micro-nano modulation layer 21 is the light-loss material. It can be understood that in this embodiment, the high refractive index and low refractive index of the materials 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 for the visible light band, and the refractive index of the light-loss material is b, and b satisfies: 3 < b < 5. At this time, the light-loss material is a high-refractive-index light-loss material for the visible light band.

[0057] The transparent protective layer 23 is disposed on the side of the transparent substrate 10 away from the photosensitive unit array and covers 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 indices of the materials 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 higher refractive index is used to increase the refractive index contrast between the overall micro-nano structure and the surrounding media, such as photoresist and the filtering substrate, so as to improve the coupling strength between the incident light field of the micro-nano structure and the waveguide light field in the micro-nano structure, and enhance the filtering and modulation ability of the micro-nano structure when the number is small. In addition, the light loss of the light-loss material will cause the quality factor Q of the resonance in the transparent substrate 10 to decrease, which is conducive to the accurate reconstruction of subsequent colors after broadband modulation.

[0059] It can be understood that when light enters from one medium into another medium, if the refractive index difference 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 indices of the transparent substrate 10 and the transparent protective layer 23, the refractive index difference between adjacent media decreases from the incident end to the transmission end of the filter micro-nano structure, so as to improve the transmittance in this embodiment.

[0060] It is not difficult to see that in this embodiment, the filter micro-nano structure 20 is designed as a double-layer modulation layer structure formed by laminating modulation layers made of a light-loss material with a relatively high refractive index and a transparent material with a relatively low refractive index respectively. This double-layer modulation layer structure combines the high transmittance and high modulation characteristics of both the light-loss material with a relatively high refractive index and the transparent material with a relatively low refractive index. It not only improves the transmittance of incident light but also ensures that the filter micro-nano structure still has a strong broadband spectral modulation ability under the small-size pixel arrangement at several wavelengths. Furthermore, it can realize the color imaging function under low illumination conditions, and can improve the overall broadband spectral modulation ability of the filter in the case of a small-size pixel and a decrease in spectral modulation ability caused by the decrease in refractive index contrast after the transparent protective layer 23, ensuring that the filter still has a strong broadband spectral modulation ability 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 require additional preparation of a multi-layer coating filter, thus 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 indices of both Si3N4 and TiO2 are higher than those of various glass materials or silicon dioxide SiO2 used for filters.

[0063] In a possible embodiment of the present application, the light-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 layer thickness H2 of the modulation layer made of the light-loss material satisfies 10nm ≤ H2 ≤ 100nm. At this time, it can ensure that the micro-nano structure has a large light flux, such as greater than 60%, and enhance the broadband modulation ability of the filter under the small arrangement of the micro-nano structure, avoiding the decrease in broadband modulation ability.

[0064] In a possible embodiment of the present application, both the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are constructed as columnar structures, and the cross-sectional shapes of both the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are rotationally symmetric 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 this 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 between the plane parallel to the plane where the transparent substrate 10 is located and the modulation layer. In this embodiment, the cross-sectional shapes of both the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are rotationally symmetric figures with a rotation angle of 90° to ensure the polarization-independent characteristics of spectral modulation, thereby maintaining the high transmittance of the micro-nano structure. For example, please refer to Figure 2and Figure 3 For a rotationally symmetric image with a rotation angle of 90°, it can be a circle, a square, an annular shape, etc.

[0066] In a possible embodiment of the present application, please refer to Figure 1 , the thickness of the transparent substrate 10 is H1, and H1>5λ. λ is the average wavelength in the visible light band. At this time, the broadband modulation interference caused by Fabry-Perot 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, where 0.2≤η≤0.8, to ensure that the double-layer modulation structure is convenient for etching preparation by techniques such as ICP (inductively coupled plasma) etching technology. Among them, the overall duty cycle is the ratio of the cross-sectional width of the columnar structure to the total height of the double-layer modulation structure.

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

[0069] In a second aspect, please refer to Figure 5 , the present application provides a filter array. 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 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 filter micro-nano structure array disposed on one side of the first transparent substrate. The filter micro-nano structure array includes a plurality of filter micro-nano structures 20 arranged in a rectangular array, and the filter micro-nano structure 20 is constructed as the filter micro-nano structure 20 provided in the foregoing embodiment.

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

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

[0073] It can be understood that referring to Figure 5 , the filter array includes a transparent dielectric layer facing all the photosensitive units. The transparent dielectric layer is divided into a plurality of block-shaped transparent substrates 10 through the sub-region array. At this time, each transparent substrate 10 combines with the filter structure provided thereon to form a filter.

[0074] Among them, the filter structure can be configured as a filter micro-nano structure array, and each filter micro-nano structure 20 in the filter micro-nano structure array is configured as the filter micro-nano structure 20 provided in the foregoing embodiment. It can also be an existing filter structure. This embodiment does not limit this, as long as at least one color corresponding filter has the filter micro-nano structure 20 provided in the foregoing embodiment.

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

[0076] For a filter whose filter structure can be configured as the filter micro-nano structure 20 provided in the foregoing embodiment, on a single transparent substrate 10, referring to Figure 6 , a plurality of identical filter micro-nano structures 20 are arranged at intervals in a rectangular array, thereby forming a filter micro-nano structure array. At this time, the filter micro-nano structure array has corresponding spectral modulation capabilities, that is, it allows the light rays in some light bands to pass through, while the light rays in the remaining light bands are not allowed to pass through. That is, it allows the light rays of one color to pass through.

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

[0078] The pitch P is also the arrangement period of the filter micro-nano structures in the filter micro-nano structure array. At this time, H3 > 300 mm combined with 100 nm ≤ P ≤ 600 nm will reduce the interaction between spectral channels, such as resonance, etc., so as to ensure that the filter micro-nano structure 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 through 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 disposed on the side of the second transparent substrate facing away from the photosensitive unit array. Among them, the second transparent substrate is the transparent substrate 10 corresponding to a sub-region in the transparent dielectric layer.

[0081] It can be understood that no micro-nano structure is provided on the transparent substrate 10 corresponding to at least one sub-region in the macro-pixel region, and all the light in the visible light band can pass through some spaces. At this time, the filter disposed 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 all-pass light energy, which can further improve the overall light transmittance of the filter array.

[0082] Specifically, in a possible embodiment of the present application, the macro-pixel region includes 1 first filter 100, 1 second filter 200, and 2 third filters 300, and 1 first filter 100, 1 second filter 200, and 2 third filters 300 are arranged in a 2×2 array; among them, the first filter 100 and the second filter 200 have the filter micro-nano structures provided in the foregoing embodiments.

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

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

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

[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 symmetric figure with a rotation angle of 90°. Therefore, when the cross-sectional shapes of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 in the first filter 100 are circular, the cross-sectional width D1 is the cross-sectional diameter of the columnar structure. When the cross-sectional shapes of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 in the first filter 100 are square, the cross-sectional width D1 is the side length dimension of the cross-section of the columnar structure. And the pitch P1 is the arrangement period of the filter micro-nano structures 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 < 200 nm, and the distance between the central axes of adjacent filter micro-nano structures is P2, 350 nm < P2 < 450 nm.

[0088] That is, when the cross-sectional shapes of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 in the second filter 200 are circular, the cross-sectional width D2 is the cross-sectional diameter of the columnar structure. When the cross-sectional shapes of the first micro-nano modulation layer 21 and the second micro-nano modulation layer 22 are square, the cross-sectional width D2 is the side length dimension of the cross-section of the columnar structure. And the pitch P2 is the arrangement period of the filter micro-nano structures in the filter micro-nano structure array.

[0089] The combination effect of the preferably provided arrangement period and shape dimension parameters in this embodiment is relatively good, and it can enable the filter array to still have a broadband modulation function for accurately reconstructing colors under low illuminance in small-sized pixels.

[0090] In a possible embodiment of the present application, in the first diagonal direction of the macro-pixel region, 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 macro-pixel region, at least two third filters 300 are arranged in sequence.

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

[0092] Please refer to Figure 5, for the upper left 2×2 macro-pixel region in a regional array, the first filter 100 is located in the upper left sub-region, the second filter 200 is located in the lower right sub-region, and the two third filters 300 are respectively located in the upper right and lower left sub-regions. 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, preferably both, have the filter micro-nano structure 20 provided in the foregoing embodiment.

[0093] Subsequently, taking both of them having the filter micro-nano structure 20 provided in the foregoing embodiment and the third filter 300 being a visible light all-pass filter as an example, 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 received energy values of the third filter 300 are approximately the same, which can be expressed as C. All the filter micro-nano structures 20 in the first filter 100 and the second filter 200 together provide n spectral modulation channels. At this time, the light energy values I1, I2, and I3 of the three colors received by the macro-pixel region are expressed as:

[0094] Equation 1:

[0095] Among them, A is the modulation matrix composed of the broadband modulation curves M1, M2, and C, and φ n is the incident spectrum of the nth spectral modulation channel. Using the compressive sensing algorithm, Equation 1 can be solved to obtain the incident spectrum corresponding to the macro-pixel, and then the color RGB values of the incident light at the macro-pixel position are as follows:

[0096]

[0097] It can be understood that the compressive 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 as close as possible to the linear combination of the R, G, and B curves. That is, at this time, M1 and M2 satisfy: min||M i -(a·R + b·G + c·B)||2, i = 1, 2. Among them, a, b, and 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 is understandable that the first filter 100 and the second filter 200 allow light of different colors to pass through, that is, the specific structures of the filter micro-nano structure arrays in the first filter 100 and the second filter 200 are different. Specifically, it may include at least one of different shapes of individual micro-nano structures, different spacings between adjacent micro-nano structures, or different numbers of micro-nano structures.

[0099] To enable those skilled in the art to better understand the protection scope of the claims of this application, the following uses specific implementation examples to explain and illustrate the technical solutions recorded in the claims of this application. It can be understood that the following examples are only used to explain this application and are not used to limit the protection scope of the claims of this application. In the following examples, the combined effects of the structural height, arrangement period, and shape size parameters of the modulation layer are relatively good, enabling the filter array to still have the broadband modulation function of accurately reconstructing colors under low illuminance in small-sized pixels.

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

[0101] The height range of the second micro-nano modulation layer 22 is between 200 - 1000 nm, and the spacing is between 200 - 500 nm to ensure that there are several waveguide modes in the double-layer modulation structure for modulation. To ensure a large light flux and enhance the broadband modulation ability with a small number of micro-nano structures, the height of the first micro-nano modulation layer 21 is between 20 - 100 nm. 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 fabricate.

[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 filter micro-nano structure 20 provided in Example 1 is used to form the first filter 100, and the filter micro-nano structure 20 provided in Example 2 is used to form the second filter 200. In a 2×2 macro-pixel region, the first filter 100 is located in the upper-left sub-region, the second filter 200 is located in the lower-right sub-region, and two third filters 300 that allow white light to pass through are respectively located in the upper-right and lower-left sub-regions.

[0106] Please refer to Figure 7 , which 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. Please refer to Figure 8 , Figure 8 The left image is the reference image, and the reference image is the true value image; Figure 8 The right image in is the color image reconstructed using the high transmittance broadband modulation curves of Example 1 and Example 2. The color accuracy of the color image is measured by the quantization index ΔE (delta-E). The average value of the color deviation ΔE of the color image is as low as 0.87, indicating that the filter arrays of Example 1 and Example 2 accurately reconstruct the image color.

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

[0108] The height of the first micro-nano modulation layer 21 is between 200 - 1500 nm, and the spacing P is between 200 - 500 nm to ensure that there are several waveguide modes in the double-layer modulation structure for modulation. To ensure a large light flux and modulation ability, the height of the second micro-nano modulation layer 22 is between 30 - 200 nm. 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, ensuring that the structure is easy to etch and fabricate.

[0109] Based on the above Structure Two, 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 filter micro-nano structure 20 provided in Example 3 is used to form the first filter 100, and the filter micro-nano structure 20 provided in Example 4 is used to form the second filter 200. In a 2×2 macro-pixel region, the first filter 100 is located in the upper left sub-region, the second filter 200 is located in the lower right sub-region, and the two third filters 300 that allow white light to pass through are respectively located in the upper right and lower left sub-regions.

[0113] Please refer to Figure 9 , which shows the high transmittance broadband modulation curves of Example 3 and Example 4. It can be seen that the high transmittance broadband modulation curves of Example 3 and Example 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, indicating that the filter arrays of Example 3 and Example 4 accurately reconstruct the image color.

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

[0115] The height of the first micro-nano modulation layer 21 is between 20 - 100 nm, and the pitch P is between 200 - 500 nm to ensure that there are several waveguide modes in the double-layer modulation structure for modulation. To ensure a large optical flux and modulation ability, the height of the second micro-nano modulation layer 22 is between 200 - 1000 nm. 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, ensuring that the structure is easy to etch and fabricate.

[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 pitch 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 pitch is 271.6 nm, and the duty cycle is 0.62.

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

[0120] Please refer to Figure 10 , which are the high transmittance broadband modulation curves of Example 5 and Example 6. It can be seen that the high transmittance broadband modulation curves of Example 5 and Example 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, indicating that the filter arrays of Example 5 and Example 6 accurately reconstruct the image color.

[0121] The above are only optional embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structural transformation made under the inventive concept of the present application by using the content of the specification and drawings of the present application, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present application.

Claims

1. A filter 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; Wherein, 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; 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.

2. The filter 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°.

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

4. The filter 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.

5. The filter 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.

6. 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 5.

7. The filter array according to claim 6, wherein 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.

8. The filter array according to claim 7, wherein 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.

9. The filter array according to claim 8, wherein The macro-pixel region includes 1 of the first filter, 1 of the second filter, and 2 of the third filters, and the 1 first filter, 1 second filter, and 2 third filters are arranged in a 2×2 array; Among them, both the first filter and the second filter have the filter micro-nano structure as described in any one of claims 1 to 6.

10. The filter array according to claim 9, wherein The side length of the first transparent substrate is e, and e satisfies: e ≤ 3um; Among them, in the first filter, the cross-sectional widths of the first micro-nano modulation layer and the second micro-nano modulation layer are D1, and D1 satisfies: 100 < D1 < 140nm, and the distance between the central axes of adjacent filter micro-nano structures is P1, and P1 satisfies 200 < P1 < 300nm; in the second filter, the cross-sectional widths of the first micro-nano modulation layer and the second micro-nano modulation layer are D2, 160 < D2 < 200nm, and the distance between the central axes of adjacent filter micro-nano structures is P2, 350nm < P2 < 450nm.

11. The filter array according to claim 8, wherein, In the first diagonal direction of the macro-pixel region, at least one of the first filters and at least one of the second filters are arranged alternately in sequence; In the second diagonal direction of the macro-pixel region, at least two of the third filters are arranged in sequence; Among them, the first diagonal direction and the second diagonal direction are parallel or perpendicular to each other.

Images