Optical filter and device

Abstract

The invention discloses an optical filter and device, and relates to the technical field of optical devices, the optical filter provided by the invention comprises a substrate and a grating array, the substrate can provide support for the grating array, the grating array is located on the substrate, the grating array is a dielectric grating array, the dielectric grating array is in contact connection with the substrate, and the dielectric grating array is located on the substrate. The difference value between the first refractive index of the grating array at the first wavelength light and the second refractive index of the substrate at the first wavelength light is larger than 0.2, and the wavelength of the first wavelength light is within the visible light wavelength range. According to the technical scheme, the single-layer dielectric material grating is arranged on the substrate, the scheme is relatively simple, the stretchable color filter device can be designed by adopting the flexible substrate, and the filtering effect is relatively more excellent.

Description

Technical Field

[0001] The present application relates to the technical field of optical devices, and in particular to an optical filter and a device. Background Art

[0002] Traditional color filter devices have the disadvantages of complex structure, difficult processing, low filtering efficiency, low color purity and color saturation, and non-tunability. They cannot meet the requirements of optical display devices for narrow-band filtering of the full spectrum of visible light, high filtering efficiency, high resolution, and wide field of view. With the development of science and technology, filters based on nano-grating structures have become a new focus. The grating structure is the earliest and most commonly used optical structure, which can realize functions such as polarization, phase control matching, and dispersion.

[0003] In the prior art, the filter based on the grating structure has a relatively complex structure, a complicated implementation scheme, and a low filtering effect. There are defects such as a large half-maximum full width, low filtering color purity, and low filtering efficiency. In addition, the polarization dependence effect produced by the color filter in the prior art is not significant, and there is no obvious difference in the filtering effect produced under incident light of different polarization states. Summary of the invention

[0004] The present application provides a filter and a device, which can achieve polarization-dependent or polarization-independent high-efficiency red, green and blue filtering characteristics by designing a one-dimensional or two-dimensional high-refractive index dielectric grating on a substrate, and can achieve tuning of the filtering band through a certain degree of stretching.

[0005] In a first aspect, the present application provides an optical filter, the optical filter comprising a substrate and a grating array, the grating array being located on the substrate, the substrate being used to support the grating array; the grating array being a dielectric grating array, the dielectric grating array being in contact with the substrate, the difference between the first refractive index of the grating array at a first wavelength of light and the second refractive index of the substrate at the first wavelength of light being greater than 0.2, and the wavelength of the first wavelength of light being within the visible light wavelength range. By adopting a high refractive index dielectric material grating structure for nanoscale design, a sub-wavelength color filter device with reflective color enhancement filtering can be realized, which can improve the saturation of reflective color rendering.

[0006] In a possible implementation, the grating array includes a one-dimensional grating array, and the one-dimensional grating array includes a plurality of one-dimensional array units periodically arranged along a first direction. The one-dimensional array unit is used to design the grating structure, and high-saturation red, green and blue grating structures can be realized respectively.

[0007] In a possible implementation, an arrangement period of the one-dimensional grating array is in a range of 420 nanometers to 500 nanometers.

[0008] In a possible implementation, the length of the one-dimensional array unit in the first direction is in the range of 220 nanometers to 320 nanometers. The one-dimensional grating structure exhibits nearly perfect reflection characteristics in the transverse electric wave mode, and the reflection intensity of red, green and blue colors exceeds 98%.

[0009] In a possible implementation, the grating array includes a two-dimensional grating array, and the two-dimensional grating array includes a plurality of two-dimensional array units periodically arranged along a second direction and a third direction, and the second direction and the third direction are inclined or perpendicular to each other. Due to the symmetrical configuration of the two-dimensional grating, the electromagnetic properties under transverse electric wave and transverse magnetic wave polarized light are the same, and the regulation is independent of polarization properties.

[0010] In a possible implementation, the two-dimensional grating array has equal periods in the second direction and / or the third direction. The two-dimensional grating array has equal periods in two directions, has a symmetrical configuration, and achieves polarization independence.

[0011] In a possible implementation, the period of the two-dimensional grating array in the second direction is in the range of 440 nanometers to 480 nanometers, and / or the period of the two-dimensional grating array in the third direction is in the range of 440 nanometers to 480 nanometers. By using two-dimensional array units to design grating structures of different sizes, high saturation red, green and blue grating structures can be realized respectively.

[0012] In a possible implementation, the lengths of the plurality of two-dimensional array units in the second direction and / or the third direction are equal. In a possible implementation, the lengths of a single two-dimensional array unit in the second direction and the third direction are equal.

[0013] In a possible implementation, the length of the two-dimensional array unit in the second direction is in the range of 300 nanometers to 380 nanometers, and / or the length of the two-dimensional array unit in the third direction is in the range of 300 nanometers to 380 nanometers. In a possible implementation, the height of the grating array is in the range of 100 nanometers to 1 micrometer. Within a certain size range, the two-dimensional grating array has good reflection characteristics, and the reflection intensity of red, green and blue colors exceeds 99%.

[0014] In a second aspect, the present application provides a device, and the device provided by the present application includes any one of the filters described above.

[0015] In a possible implementation, the device includes a display module, the display module also includes a polarizing layer and a display layer, and the display layer is located between the filter and the polarizing layer. The display module may not use a traditional color filter, but a sub-pixel filter to achieve the purpose of color display.

[0016] In a possible implementation, the display layer includes a first electrode layer, a second electrode layer and a liquid crystal layer, and the liquid crystal layer is located between the first electrode layer and the second electrode layer. The electrode layer has a transparent property to realize reflective display, the filter has a very narrow reflection spectrum, and the display module has a higher color gamut than a traditional display module.

[0017] In a possible implementation, the device includes a color-developing surface, and the color-developing surface also includes a stretcher, and the stretcher is arranged at the edge of the filter and is used to change the period of the grating array. The color-developing surface can be stretched by the stretcher, and the color-developing surface will show different reflected colors when the stretching amount is different.

[0018] In a possible implementation, the device includes a refractive index detector, which also includes a light source and a wavelength detector. The light source and the wavelength detector are located on a side of the filter close to the grating array, the light source is used to emit light to the filter, and the wavelength detector is used to detect the reflected light of the filter. As the refractive index of the environment increases, the refractive index detector can see an obvious red shift of the resonance peak, and the refractive index of the medium can be accurately determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of a filter with a one-dimensional grating array structure provided in an embodiment of the present application;

[0020] Figure 2 is a schematic diagram of a filter with a two-dimensional grating array structure provided in an embodiment of the present application;

[0021] Figure 3 is a schematic diagram of the reflection spectrum of the filter with a one-dimensional grating array structure provided in an embodiment of the present application;

[0022] Figure 4 is a schematic diagram of the reflection spectrum of the filter with a two-dimensional grating array structure provided in an embodiment of the present application;

[0023] Figure 5 is a schematic diagram of the display module structure provided in an embodiment of the present application;

[0024] Figure 6 It is a schematic diagram of the structure of a display module with a light guide plate provided in an embodiment of the present application;

[0025] Figure 7 is a schematic diagram of a color display surface provided in an embodiment of the present application;

[0026] Figure 8 It is a schematic diagram of the reflection spectrum of the color display surface of the two-dimensional grating array structure provided in the embodiment of the present application;

[0027] Fig. 9 is a schematic diagram of a refractive index detector provided in an embodiment of the present application;

[0028] Fig.10 Schematic diagram of the reflection spectrum of the refractive index detector provided in the embodiment of the present application in different environmental media;

[0029] Fig.11 It is a schematic diagram of a method for preparing an optical filter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0031] For ease of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are explained and described below.

[0032] It should be clear that 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 the field without creative work are within the scope of protection of the present application.

[0033] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0034] It should be understood that the term "and / or" used in this article is only a description of the same field of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0035] It should be understood that the terms “first”, “second”, etc. used in the present application are only used for the purpose of distinguishing the description, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying an order.

[0036] In the description of the present application, the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0037] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection or an integrated connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0038] When used in this application, “within the range of…”, unless it is separately specified that an end value is not included, it is assumed that both end values ​​of the range are included. For example, in the range of 1 to 5, the two values ​​1 and 5 are included.

[0039] Traditional color filters are mainly composed of glass substrates, black matrices, color layers, optical adhesives and conductive films, and there are many problems in their production process. Common color filter production methods include pigment dispersion, dyeing, printing and electrodeposition. However, these methods still have limitations in color reproduction, color saturation, production quality and cost, and have not reached the level of meeting market demand. The performance of color filters directly affects the contrast, brightness, viewing angle and picture quality of the display. In order to ensure that the liquid crystal display device has sufficient demand for the performance of color filters, color filters need to have high color purity and high contrast. High color purity means that the transmission spectrum bandwidth of the three basic colors of the color filter, namely the three primary colors of red, green and blue, should be moderate and not too narrow or too wide. If the transmission wavelength range is too narrow, the transmittance will be reduced and the true color cannot be displayed; while the transmission wavelength is too wide, the spectrum of the three basic colors will overlap, which will reduce the color reproduction ability of the color filter layer. In addition, high contrast is also one of the important properties of color filters. High contrast requires color filters to have higher transmittance. The raw materials and production process of the filters also have a certain impact on the transmittance.

[0040] With the development of science and technology, people have proposed color filters based on nanostructured gratings. The grating structure is the earliest and most commonly used optical structure, which can realize functions such as polarization, phase control matching and dispersion. The subwavelength of the visible light band, that is, the one-dimensional grating structure at the nanoscale, has excellent polarization characteristics, full-spectrum polarization characteristics of visible light, high transmittance / reflectivity and other superior characteristics; while the two-dimensional subwavelength grating structure can realize the control of polarization characteristics, and can produce polarization-independent characteristics when the structure is completely symmetrical in two dimensions, and at the same time it can also have other excellent characteristics of the one-dimensional grating structure. Therefore, the two-dimensional metasurface is considered to be an alternative nanostructure in practical optoelectronic applications. Compared with traditional color filters, the manufacturing method of filters based on nanostructured gratings is more flexible and diversified. It can be processed by photolithography and nanoimprinting processes, which can reduce processing costs, improve production efficiency, and have high light energy utilization, ensuring that the color display of the display screen is fuller and more realistic. Color filter technology based on nanostructured gratings has begun to be widely used, providing a better solution for the picture quality of liquid crystal displays.

[0041] The present application provides a filter, see Figure 1 and Figure 2 As shown, the optical filter based on the grating structure provided in the embodiment of the present application includes a substrate 100 and a grating array 200 .

[0042] The substrate 100 may be made of transparent materials, including polymethyl methacrylate, polydimethylsiloxane or silicon dioxide. The substrate 100 may provide support for the grating array 200, and the substrate 100 may also participate in the refraction of light. The embodiment of the present application is described by taking the substrate 100 as an example of using polydimethylsiloxane material.

[0043] The grating array 200 may use a high refractive index dielectric material, the high refractive index dielectric material includes a first wavelength light in the visible light wavelength range (380 nanometers to 750 nanometers), and the difference between the first refractive index through the grating array and the second refractive index through the substrate is greater than 0.2. The embodiment of the present application is described by taking the grating array 200 using silicon nitride, i.e., Si3N4 material as an example. The grating array 200 may include a plurality of periodically arranged array units 210. It should be noted that the difference between the first refractive index and the second refractive index through the substrate is greater than 0.2, and there may be an error of less than 30% during measurement.

[0044] In the implementation manner of the present application, a single-layer dielectric material grating is set on a transparent substrate, the structure is simple, and the preparation scheme is relatively simple. Reflective red, green and blue filtering can be achieved with excellent filtering effect.

[0045] The embodiments of the present application can use transparent materials such as polymethyl methacrylate, polydimethylsiloxane or silicon dioxide as the substrate of the filter device, and use high refractive index materials to prepare the grating structure for nano-level design. By designing a one-dimensional or two-dimensional silicon nitride grating metasurface structure on the substrate 100, high-efficiency red, green and blue filtering characteristics that are polarization-dependent or polarization-independent can be achieved under certain structural parameters, and the filter band can be tuned by stretching the flexible substrate to a certain extent, and the device performance of refractive index sensing can be achieved.

[0046] In one possible implementation, see Figure 1 As shown, the grating array 200 in the embodiment of the present application may be a one-dimensional grating array 200 arranged periodically along one direction. The arrangement direction of the one-dimensional grating array 200 is a first direction 310. The one-dimensional grating array 200 includes a plurality of array units 210 arranged periodically along the first direction 310. The plurality of array units 210 are periodically arranged along the first direction 310 to form the one-dimensional grating array 200.

[0047] In a possible implementation, the one-dimensional grating array 200 includes a plurality of repeatable minimum array units 210. The period of the one-dimensional grating array 200 is denoted as P1, and the period P1 of the one-dimensional grating array 200 is the distance from a repeatable minimum array unit 210 to an adjacent repeatable minimum array unit 210 along the first direction 310. The length of the repeatable minimum array unit 210 along the first direction is denoted as W1. The height of the repeatable minimum array unit 210 in a direction perpendicular to the substrate 100 is denoted as H1.

[0048] In a possible implementation, the period P1 of the one-dimensional grating array 200 in the implementation of the present application is in the range of 420 nanometers to 450 nanometers, and the length W1 of the repeatable minimum array unit 210 in the one-dimensional grating array 200 along the first direction is in the range of 220 nanometers to 320 nanometers.

[0049] In a possible implementation, a height H1 of a repeatable minimum array unit 210 in the one-dimensional grating array 200 in a direction perpendicular to the substrate 100 is in a range of 100 nanometers to 1000 nanometers.

[0050] It should be noted that due to processing errors in the preparation process, the size of the array unit 210 may have errors relative to the design range, and the design within the error range is still within the protection scope of this application.

[0051] In one possible implementation, see Figure 2As shown, the grating array 200 in the embodiment of the present application may be a two-dimensional grating array 200 that is periodically arranged along two directions. One of the arrangement directions of the two-dimensional grating array 200 is the second direction 320 , and the other arrangement direction is the third direction 330 .

[0052] The two-dimensional grating array 200 includes a plurality of array units 210 periodically arranged along the second direction 320 and the third direction 330. The plurality of array units 210 are periodically arranged along the second direction 320 and the third direction 330 to form the two-dimensional grating array 200. The period of the two-dimensional grating array 200 along the second direction is recorded as P2, and the period of the two-dimensional grating array 200 along the third direction is recorded as P3.

[0053] The period P2 of the two-dimensional grating array 200 is the distance from the repeatable minimum array unit 210 to the adjacent repeatable minimum array unit 210 along the second direction 320. The period P3 of the two-dimensional grating array 200 is the distance from the repeatable minimum array unit 210 to the adjacent repeatable minimum array unit 210 along the third direction 330. The length of the repeatable minimum array unit 210 along the second direction is recorded as W2, and the length of the repeatable minimum array unit 210 along the third direction is recorded as W3. The height of the repeatable minimum array unit 210 in the direction perpendicular to the substrate 100 is recorded as H2.

[0054] In a possible implementation, the period P2 of the two-dimensional grating array 200 in the implementation of the present application in the second direction is in the range of 440 nanometers to 480 nanometers, and the period P3 of the two-dimensional grating array 200 in the third direction is in the range of 440 nanometers to 480 nanometers.

[0055] In a possible implementation, the period P2 of the two-dimensional grating array 200 in the second direction is equal to the period P3 of the two-dimensional grating array 200 in the third direction, that is, P2 is equal to P3, and both are within the range of 440 nanometers to 480 nanometers.

[0056] In one possible implementation, the length W2 of the repeatable minimum array unit 210 in the two-dimensional grating array 200 along the second direction is in the range of 300 nanometers to 380 nanometers. The length W3 of the repeatable minimum array unit 210 in the two-dimensional grating array 200 along the third direction is in the range of 300 nanometers to 380 nanometers.

[0057] In one possible implementation, the length W2 of the repeatable minimum array unit 210 in the two-dimensional grating array 200 along the second direction is equal to the length W3 of the repeatable minimum array unit 210 in the two-dimensional grating array 200 along the third direction, that is, W2 is equal to W3, and both are in the range of 300 nanometers to 380 nanometers.

[0058] In a possible implementation, the height H2 of the repeatable minimum array unit 210 in the two-dimensional grating array 200 in the direction perpendicular to the substrate 100 is in the range of 100 nanometers to 1000 nanometers. It should be noted that due to processing errors in the preparation process, the size of the array unit 210 may have errors relative to the design range, and the design within the error range is still within the protection scope of this application.

[0059] The optical filter in the embodiment of the present application can achieve a high-efficiency light effect with a FWHM (full width at half-maximum) of less than 22 nanometers. In this embodiment, the electric field direction of the incident electromagnetic wave is set to be a transverse electric wave along the first direction. When the incident light is a transverse electric wave, the one-dimensional filter and the two-dimensional filter in the embodiment of the present application under this incident condition are equivalent to a reflective narrow-band visible light filter, which can achieve a nearly perfect reflection narrow-band color enhancement filter with a half-width value of less than 22 nanometers.

[0060] When the incident light is a transverse magnetic wave, the one-dimensional filter in the embodiment of the present application exhibits the effect of a polarizer due to its one-dimensional grating structure, and does not produce any resonant filtering; the two-dimensional filter exhibits the same resonant filtering effect as under the incidence of a transverse electric wave due to its symmetrical two-dimensional grating structure. The embodiment of the present application can significantly improve the saturation of the reflective display.

[0061] In a possible implementation, the filter in the implementation of the present application can present high saturation red, green, or blue. The filter can adopt a one-dimensional or two-dimensional grating structure, and the grating array 200 can be made of Si3N4 material.

[0062] In a possible implementation manner, the optical filter in the implementation manner of the present application may adopt a one-dimensional grating structure, and the specific structural parameters are as follows:

[0063] The structural parameters of the one-dimensional grating array 200 presenting high-saturation red are as follows: the period P1 of the one-dimensional grating array 200 is 460 nanometers, the length W of the repeatable minimum array unit 210 along the first direction is 240 nanometers, and the height H1 of the repeatable minimum array unit 210 in the direction perpendicular to the substrate 100 is 320 nanometers.

[0064] The structural parameters of the one-dimensional grating array 200 presenting high-saturation green are as follows: the period P1 of the one-dimensional grating array 200 is 370 nanometers, the length W of the repeatable minimum array unit 210 along the first direction is 170 nanometers, and the height H1 of the repeatable minimum array unit 210 in the direction perpendicular to the substrate 100 is 260 nanometers.

[0065] The structural parameters of the one-dimensional grating array 200 presenting high-saturation blue are as follows: the period P1 of the one-dimensional grating array 200 is 290 nanometers, the length W of the repeatable minimum array unit 210 along the first direction is 140 nanometers, and the height H1 of the repeatable minimum array unit 210 in the direction perpendicular to the substrate 100 is 230 nanometers.

[0066] See also Figure 3 As shown, in the transverse electric wave mode, the resonant wavelength of R (red) of the filter with a one-dimensional grating structure is about 698 nanometers, the resonant wavelength of G (green) is about 543 nanometers, and the resonant wavelength of B (blue) is about 438 nanometers. It shows nearly perfect reflection characteristics, and the reflection intensity of RGB colors exceeds 98%; the full width corresponding to the half maximum value of the bandwidth of the red (R) spectrum is about 22 nanometers, the full width corresponding to the half maximum value of the bandwidth of the green (G) spectrum is about 10 nanometers, and the full width corresponding to the half maximum value of the bandwidth of the blue (B) spectrum is about 13 nanometers. In the transverse magnetic wave mode, the reflection intensity of red (R), green (G) and blue (B) light of the filter with a one-dimensional grating structure is kept below 0.30.

[0067] In a possible implementation manner, the optical filter in the implementation manner of the present application may adopt a two-dimensional grating structure, and the specific structural parameters are as follows:

[0068] The structural parameters of the two-dimensional grating array 200 presenting high-saturation red are as follows: the period P2 of the two-dimensional grating array 200 in the second direction is equal to the period P3 of the two-dimensional grating array 200 in the third direction, both of which are 480 nanometers; the length W2 of the repeatable minimum array unit 210 along the second direction is equal to the length W3 of the repeatable minimum array unit 210 in the two-dimensional grating array 200 along the third direction, both of which are 300 nanometers; the height H2 of the repeatable minimum array unit 210 in the direction perpendicular to the substrate 100 is 260 nanometers.

[0069] The structural parameters of the two-dimensional grating array 200 presenting high-saturation green are as follows: the period P2 of the two-dimensional grating array 200 in the second direction is equal to the period P3 of the two-dimensional grating array 200 in the third direction, both of which are 370 nanometers; the length W2 of the repeatable minimum array unit 210 along the second direction is equal to the length W3 of the repeatable minimum array unit 210 in the two-dimensional grating array 200 along the third direction, both of which are 230 nanometers; the height H2 of the repeatable minimum array unit 210 in the direction perpendicular to the substrate 100 is 220 nanometers.

[0070] The structural parameters of the two-dimensional grating array 200 presenting a high-saturation blue color are as follows: the period P2 of the two-dimensional grating array 200 in the second direction is equal to the period P3 of the two-dimensional grating array 200 in the third direction, both of which are 300 nanometers; the length W2 of the repeatable minimum array unit 210 along the second direction is equal to the length W3 of the repeatable minimum array unit 210 in the two-dimensional grating array 200 along the third direction, both of which are 180 nanometers; the height H2 of the repeatable minimum array unit 210 in the direction perpendicular to the substrate 100 is 160 nanometers.

[0071] In the implementation mode of this application, refer to Figure 4 As shown, the filter using a two-dimensional grating structure has the same electromagnetic properties under transverse electric wave and transverse magnetic wave polarized light due to the symmetrical configuration of the two-dimensional grating structure in the transverse electric wave and transverse magnetic wave modes. The resonant wavelength of R (red) is about 703 nanometers, the resonant wavelength of G (green) is about 547 nanometers, and the resonant wavelength of B (blue) is about 440 nanometers. The filter with a two-dimensional grating structure has perfect reflection characteristics. The average reflection intensity of RGB colors is about 99%, the full width corresponding to the half maximum bandwidth of the red (R) spectrum is about 6 nanometers, the full width corresponding to the half maximum bandwidth of the green (G) spectrum is about 5 nanometers, and the full width corresponding to the half maximum bandwidth of the blue (B) spectrum is about 9 nanometers. The implementation method of the present application has the advantages of simpler structure and larger tuning range. Only a single-layer dielectric material grating is required, and the dimension of the grating can be changed according to the actual application needs to achieve the regulation of polarization-dependent characteristics.

[0072] In one possible implementation, see Figure 5 As shown, the present application provides a display module. The display module in the embodiments of the present application can be a reflective display module based on LCD, including a filter of any of the above embodiments, and the filter can be used as a reflective color filter unit 430 in the display module. The display module also includes a polarizing layer 410 and a display layer 420, and the display layer 420 is located between the reflective color filter unit 430 and the polarizing layer 410.

[0073] In some possible implementations, the display layer 420 in the implementation of the present application includes a first electrode layer 421, a second electrode layer 422, a liquid crystal layer 423 and a driving circuit layer 424. The liquid crystal layer 423 is located between the first electrode layer 421 and the second electrode layer 422, and the driving circuit layer can be located on one side of the first electrode layer 421, or the driving circuit layer can also be located on one side of the second electrode layer 422. The display module can also include a cover plate 440, which is connected to the polarization layer 410 to protect the display module. The LCD in the implementation of the present application does not use a traditional filter layer located in front of the liquid crystal layer to display the color of each sub-pixel, but places the reflective color filter of the present invention on the back side of the liquid crystal layer to achieve the purpose of color display. The sub-pixels of the reflective color filter correspond one-to-one to the sub-pixels of the liquid crystal layer, and the sub-pixels of the color filter may include red, green, and blue, which correspond to the structural parameters of the aforementioned red, green, and blue implementations, respectively.

[0074] When an external light source is irradiated on the reflective display module provided in the embodiment of the present application, a part of it will pass through the polarizer to become linearly polarized light. After passing through the portion of the liquid crystal layer modulated by different sub-pixel driving circuit units, the polarization angle of the linear polarized light from the outside will be changed. After being reflected by the color filter units of different colors and then passing through the liquid crystal layer and the polarizer, the above light will be distinguished into different colors and different grayscales according to the definition of the sub-pixels, thereby achieving the effect of displaying the content. Since the filter of the present application has a very narrow reflection spectrum, the reflective display module provided in the embodiment of the present application has a high color gamut that general reflective display components, such as reflective LCDs using dye color blocking filters, do not have.

[0075] In one possible implementation, see Figure 6As shown, the present application provides a display module that uses a side light source and a light guide plate 450 as an additional light source. The reflective display module in the embodiment of the present application can be a reflective display module based on LCD, including a reflective color filter unit 430, a polarizing layer 410 and a display layer 420, and the display layer 420 is located between the reflective color filter unit 430 and the polarizing layer 410; the display layer 420 includes a first electrode layer 421, a second electrode layer 422, a liquid crystal layer 423 and a driving circuit layer 424. The liquid crystal layer 423 is located between the first electrode layer 421 and the second electrode layer 422, and the driving circuit layer can be located on one side of the first electrode layer 421, or the driving circuit layer can also be located on one side of the second electrode layer 422. The display module also includes a light guide plate 450. In addition to using external ambient light for display, it can also use the additional fill light from the side light source that enters the light guide plate 450 and then enters the display component for display. The side light source can be a white LED light source belt, arranged on one side of the light guide plate 450; the upper and lower sides of the light guide plate 450 have a light-guiding structure such as a rough surface with periodic or non-periodic protrusions, so that the light from the side light source is easier to be emitted from the lower surface than from the upper surface, thereby ensuring the display effect. When the external light source is irradiated on the reflective display module provided in the embodiment of the present application, the side light source is injected into the light guide plate 450 and then into the display component to be displayed as additional fill light, and a part of the light will pass through the polarizer to become linearly polarized light. After passing through the liquid crystal layer portion modulated by different sub-pixel driving circuit units, the polarization angle of the linearly polarized light from the outside will be changed. After being reflected by the color filter units of different colors and then passing through the liquid crystal layer and the polarizer, the above light will distinguish different colors and different grayscales according to the definition of the sub-pixel, thereby achieving the effect of displaying the content. The display brightness is higher than that without the light guide plate 450 by using the additional fill light of the side light source injected into the light guide plate 450 and then into the display component.

[0076] In one possible implementation, see Figure 7 As shown, the embodiment of the present application provides a color-developing surface. The color-developing surface provided in the embodiment of the present application can be a high-saturation stretchable color-developing surface, and the color-developing surface includes the filter in the aforementioned implementation and also includes a stretching device 710.

[0077] The substrate 100 of the filter in the embodiment of the present application can be made of a flexible transparent material, for example, the substrate 100 can be made of polydimethylsiloxane. The color-developing surface can be stretched under the action of the clamp, and the stretching device 710 can pull the clamp to stretch quantitatively in different directions. The color-developing surface is stretched under the action of the clamp, and the reflected color of the stretched color-developing surface will be red-shifted, and the color-developing surface will show different reflected colors when the stretching amount is different.

[0078] This embodiment is described by taking a color filter with a two-dimensional grating structure as an example, defining the x direction to be parallel to the second direction, and the y direction to be parallel to the third direction, and the corresponding grating structure parameters are as follows: the period P2 of the two-dimensional grating array 200 in the second direction is equal to the period P3 of the two-dimensional grating array 200 in the third direction, both of which are 400 nanometers; the length W2 of the repeatable minimum array unit 210 along the second direction is equal to the length W3 of the repeatable minimum array unit 210 in the two-dimensional grating array 200 along the third direction, both of which are 300 nanometers; the height H2 of the repeatable minimum array unit 210 in the direction perpendicular to the substrate 100 is 260 nanometers. Figure 8 The three figures on the left, middle and right respectively show the dynamically tuned reflection spectra of transverse electric wave mode light under different stretching degrees along different directions.

[0079] Stretching the color filter in different directions is equivalent to increasing the period value of the grating array 200. The greater the stretching amount, the greater the red shift of the reflection peak. Figure 8 As shown on the left, as the stretching amount in the x direction gradually increases, the resonance wavelength also gradually increases; when the stretching amount in the x direction is 0, the resonance wavelength is about 620 nanometers, and when the stretching amount in the x direction is 25%, the resonance wavelength redshifts from 620 nanometers to 710 nanometers; Figure 8 As shown in the middle, as the stretching amount in the y direction gradually increases, the change in the resonance wavelength is small, indicating that the resonance wavelength red shift is small when stretching in the y direction; Figure 8 As shown on the right, when stretched in the xy oblique direction, the resonance is red-shifted from 550 nanometers to 735 nanometers. In other words, different stretching amounts can correspond to different colors, and the colors of reflected light in different polarization directions can be adjusted separately.

[0080] The color-developing surface provided in the embodiment of the present application can infinitely adjust the color development by stretching, and the color-developing surface before and after stretching has a very narrow reflection spectrum, that is, a very high color saturation. This stretchable and tunable color-developing surface can conveniently display different high-saturation reflection colors, and the color can be accurately adjusted by mechanical stretching, and can be used for high-saturation reference color cards. Compared with general printed reference color cards, this embodiment can achieve infinite tuning, is more convenient to use, and has a much higher saturation than general printed reference color cards.

[0081] In one possible implementation, see Fig. 9 As shown, the embodiment of the present application provides an environmental medium refractive index detector. The environmental medium refractive index detector provided by the embodiment of the present application includes a light source 810, a wavelength detector 820 and a color filter surface 830, and the color filter surface 830 includes the filter described in the present invention.

[0082] The light source 810 irradiates the color filter surface through the transparent container, and the reflected light passes through the transparent container and is captured by the wavelength detector 820. In environments with different refractive indices, the reflection spectrum of the filter is different, and the refractive index of the environment can be detected through the reflection spectrum of the filter.

[0083] Fig.10 The reflection spectra of the transverse electric wave mode light in the medium with different refractive indexes in the range of 1.3 to 1.5 are respectively shown for one-dimensional grating structure filter and two-dimensional grating structure filter. As the refractive index increases, for example, the refractive index of the ambient medium increases from 1.3 to 1.5, the reflection spectrum can show an obvious red shift of the resonance peak, which can accurately determine the refractive index of the medium.

[0084] like Fig.10 For the filter with a one-dimensional grating structure, the reflection spectrum peak corresponds to a wavelength of about 735 nanometers in an ambient medium with a refractive index of 1.3, the reflection spectrum peak corresponds to a wavelength of about 740 nanometers in an ambient medium with a refractive index of 1.34, the reflection spectrum peak corresponds to a wavelength of about 745 nanometers in an ambient medium with a refractive index of 1.38, the reflection spectrum peak corresponds to a wavelength of about 750 nanometers in an ambient medium with a refractive index of 1.42, the reflection spectrum peak corresponds to a wavelength of about 760 nanometers in an ambient medium with a refractive index of 1.46, and the reflection spectrum peak corresponds to a wavelength of about 765 nanometers in an ambient medium with a refractive index of 1.46.

[0085] Compared with the currently common refractometers, which require sampling and testing at different times, this embodiment can monitor the refractive index in real time during temperature and pressure changes, heat transfer, and mass transfer processes, thereby understanding the state of the ambient medium.

[0086] In one possible implementation, see Fig.11 As shown, the present application embodiment provides a method for preparing the optical filter described in the above embodiment, comprising the following steps:

[0087] Step S100 , preparing a substrate 100 ; the substrate 100 may be made of a transparent material, such as polydimethylsiloxane.

[0088] Step S200, depositing a dielectric layer on the substrate; specifically, the dielectric layer may be deposited on the substrate using an inductively coupled plasma chemical vapor deposition process, and the dielectric layer may use a dielectric material with a high refractive index, such as silicon nitride.

[0089] Step S300 , patterning the dielectric layer to generate a matrix-arranged grating structure pattern to form an optical filter.

[0090] Specifically, in a possible implementation manner, step S300 may include the following steps:

[0091] Step S301, coating a positive photoresist on the dielectric film; the illuminated area of ​​the positive photoresist can be developed away, and the photoresist in other areas not illuminated can be left.

[0092] Step S302, using photolithography and development to generate a grating structure pattern; an electron beam lithography process can be used to use focused electrons with extremely short wavelengths to directly act on the surface of a photoresist that is sensitive to electrons to draw and form a grating structure pattern.

[0093] Step S303, etching the dielectric film until the substrate to form a dielectric grating array 200; a reactive ion etching process may be used to etch the silicon nitride film to the substrate to form a silicon nitride dielectric grating.

[0094] Step S304, removing the photoresist remaining on the dielectric grating, and completing the preparation of the optical filter. Using an oxygen plasma method, the photoresist remaining on the silicon nitride dielectric grating is removed, and the preparation of the optical filter device is completed.

[0095] The preparation process of the metasurface filter provided in the embodiment of the present application is simple, and the device can be prepared through only three processes: CVD (Chemical Vapor Deposition), EBL (Electron Beam Lithography) and RIE (Reactive Ion Etching). The industry only needs to prepare a mask of the corresponding shape to achieve large-scale mass production. By converting the EBL process to a precision lithography process, it can complete the process challenges of large-area, small-scale, i.e., nano-level, and batch manufacturing that other sub-wavelength devices cannot achieve.

[0096] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A filter, characterized in that: include: A substrate and a grating array, wherein the grating array is located on the substrate, and the substrate is used to support the grating array; The grating array is a dielectric grating array, the dielectric grating array is in contact with the substrate, a difference between a first refractive index of the grating array at a first wavelength of light and a second refractive index of the substrate at the first wavelength of light is greater than 0.2, and the wavelength of the first wavelength of light is within the visible light wavelength range.

2. The optical filter according to claim 1, characterized in that The grating array includes a one-dimensional grating array, and the one-dimensional grating array includes a plurality of one-dimensional array units periodically arranged along a first direction.

3. The optical filter according to claim 2, characterized in that The arrangement period of the one-dimensional grating array is in the range of 420 nanometers to 500 nanometers.

4. The optical filter according to claim 2 or 3, characterized in that The sizes of the multiple one-dimensional array units are equal.

5. The optical filter according to any one of claims 2 to 4, characterized in that: The length of the one-dimensional array unit in the first direction is in the range of 220 nanometers to 320 nanometers.

6. The optical filter according to claim 1, characterized in that The grating array includes a two-dimensional grating array, and the two-dimensional grating array includes a plurality of two-dimensional array units periodically arranged along a second direction and a third direction, and the second direction and the third direction are inclined or perpendicular to each other.

7. The optical filter according to claim 6, characterized in that The two-dimensional grating array has the same period in the second direction and / or the third direction.

8. The optical filter according to claim 6 or 7, characterized in that The period of the two-dimensional grating array in the second direction is within a range of 440 nanometers to 480 nanometers, and / or the period of the two-dimensional grating array in the third direction is within a range of 440 nanometers to 480 nanometers.

9. The optical filter according to any one of claims 6 to 8, characterized in that: The lengths of the plurality of two-dimensional array units in the second direction and / or the third direction are equal.

10. The optical filter according to any one of claims 6 to 9, characterized in that: The length of a single two-dimensional array unit in the second direction is equal to the length of the third direction.

11. The optical filter according to any one of claims 6 to 10, characterized in that: The length of the two-dimensional array unit in the second direction is in the range of 300 nanometers to 380 nanometers, and / or the length of the two-dimensional array unit in the third direction is in the range of 300 nanometers to 380 nanometers.

12. The optical filter according to any one of claims 1 to 11, characterized in that: The height of the grating array is in the range of 100 nanometers to 1 micrometer.

13. A device, characterized in that: The optical filter comprises the optical filter according to any one of claims 1 to 11.

14. The device according to claim 13, characterized in that The device comprises a display module, wherein the display module further comprises a polarizing layer and a display layer, wherein the display layer is located between the filter and the polarizing layer.

15. The device according to claim 14, characterized in that The display layer includes a first electrode layer, a second electrode layer and a liquid crystal layer, and the liquid crystal layer is located between the first electrode layer and the second electrode layer.

16. The device according to claim 13, characterized in that The device comprises a color developing surface, and the color developing surface further comprises a stretcher, wherein the stretcher is arranged at the edge of the filter and is used for changing the period of the grating array.

17. The device according to claim 13, characterized in that The device includes a refractive index detector, which also includes a light source and a wavelength detector. The light source and the wavelength detector are located on a side of the filter close to the grating array. The light source is used to emit light to the filter, and the wavelength detector is used to detect the reflected light of the filter.

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