Reflection type color filtering structure

Abstract

The utility model discloses a reflective color filter structure which comprises a substrate, a plurality of nanostructures distributed in an array mode are arranged on the substrate, and the nanostructures comprise more than two layers of metal nanostructures and more than two layers of medium nanostructures. The metal nanostructures and the medium nanostructures are alternately laminated from bottom to top, and the top layer and the bottom layer of each nanostructure are both metal nanostructures. According to the light filtering structure, light filtering is achieved through the color reduction principle, the sensitivity to angles is low, and light filtering can be achieved within the wide angle range; by modulating the period or the duty cycle of each nano structure, the filtering effect of different colors can be realized; the reflection efficiency of the reflection valley is very low, and the light energy utilization rate is greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of filter structures, in particular to a reflective color filter structure. Background Art

[0002] Optical filter components have broad application prospects in a variety of industries, including flat-panel displays, photovoltaic energy, optical sensing, light detection, new ink-free printing technologies, optical decoration, and security signage. With the rapid advancement of micro- and nanofabrication technologies, the design and fabrication of optical filter components has become a research hotspot in micro- and nano-optics. However, most current micro- and nanostructured optical filters are extremely sensitive to the angle of incident light. Changes in the incident angle cause significant shifts in the filtered wavelength or a significant decrease in reflection efficiency, limiting their application.

[0003] Researchers are actively conducting research on wide-angle optical filtering devices. Yeo-Taek Yoon's team in South Korea constructed a polycrystalline silicon-silicon dioxide grating structure (period 446 nm) on a quartz substrate, achieving blue light transmission. However, as the incident angle increased from 0 to 15 degrees, the transmittance dropped from 40% to 18%. Hans Lochbihler in Germany proposed a dielectric-metal grating composite structure. By evaporating a "Z"-shaped aluminum grating onto a dielectric grating, he designed a transmissive filter. This filter maintains the transmission peak positions for TM (transverse magnetic) and TE (transverse electric) polarized light over an incident angle range of 0 to 30 degrees. However, the resonant peak transmission efficiency for TM polarized light is low, at only 20%. Stephen Y. Chou of Princeton University fabricated a dielectric grating array on a quartz substrate and subsequently deposited aluminum onto it using tilted-angle electron evaporation. Results showed that for unpolarized light, the transmission peak position remains essentially stable over an incident angle range of ±25 degrees, but the transmission efficiency decreases.

[0004] Therefore, research and development of a micro-nanostructure reflective filter device that improves light energy utilization and reduces angle sensitivity is of great significance for broadening the application field of micro-nanostructure filters. Summary of the Invention

[0005] The technical problem to be solved by the utility model is to provide a reflective color filter structure, which is composed of a substrate and an array-arranged nanostructure, and adopts a metal nanostructure and a dielectric nanostructure with two or more layers alternately stacked from bottom to top, and the top and bottom layers of the nanostructure are both designed as metal nanostructures. The reflective filter filters light based on the subtractive principle and has the characteristics of high light energy utilization, low angle sensitivity, high saturation and wide color gamut.

[0006] In order to solve the above technical problems, the present invention provides a reflective color filter structure, including a substrate, on which a plurality of nanostructures distributed in an array are arranged, the nanostructures including two or more layers of metal nanostructures and two or more layers of dielectric nanostructures, the metal nanostructures and dielectric nanostructures are alternately stacked from bottom to top, and the top and bottom layers of the nanostructures are both metal nanostructures.

[0007] The reflective color filter structure of the utility model is provided with an array of nanostructures on a substrate, wherein the nanostructures are arranged as two or more layers of metal nanostructures and dielectric nanostructures in an alternating stacking design, and both the bottom and top layers of the nanostructures are set as metal nanostructures. Through the plasma wave resonance between the metal nanostructures and the dielectric nanostructures, the structure can absorb light waves coupled with its surface plasma resonance frequency and reflect light waves in other bands, thereby achieving filtering effects of different colors.

[0008] This reflective filter filters light based on the principle of subtractive color. The duty ratio or period of the nanostructure corresponds to the complementary color of the structure's filtering wavelength. By adjusting its duty ratio or period, a variety of colors from yellow to cyan can be achieved, with the characteristics of a wide color gamut. At the same time, the structure's reflection spectrum is narrow, with a half-peak width of only 50 nanometers, high saturation, and more vivid colors. The reflectivity of the structure can be close to 0, and its complementary color brightness is high, which can make the light and dark contrast between colors more obvious. The structure has good angular tolerance. Within the range of incident angles from 0 to 60 degrees, the position of the reflection valley does not change much, that is, the color observed by the human eye remains basically unchanged, solving the problem of angle sensitivity during existing micro-nanostructure filtering.

[0009] Furthermore, the thickness of the metal nanostructure is 30-50 nm.

[0010] Furthermore, the thickness of the dielectric nanostructure is 20-60 nm.

[0011] Furthermore, the duty ratio of the nanostructure is 0.25-0.35, and by adjusting the duty ratio, a variety of color transitions from yellow to cyan can be achieved, with a wide color gamut.

[0012] Furthermore, the period of the arrangement of the nanostructure array is 100-300 nm.

[0013] Furthermore, the substrate is made of highly reflective metal, and its thickness is greater than the skin depth, mainly acting as a reflector. The specific material may be one or more of aluminum, silver, nickel, germanium, or other highly reflective metals.

[0014] Furthermore, the material of the metal nanostructure is aluminum and / or silver.

[0015] Furthermore, the material of the dielectric nanostructure is a high reflectivity material, specifically one or more of gallium arsenide, iron oxide, gallium nitride, zinc sulfide, titanium dioxide, or other high reflectivity dielectric materials.

[0016] Furthermore, the number of layers of the metal nanostructure is three, and the number of layers of the dielectric nanostructure is two.

[0017] Furthermore, the cross-sectional distribution of all the nanostructures is in the shape of a grating, a square array, a rectangular array, a circular array or an elliptical array.

[0018] Beneficial effects of the utility model:

[0019] The reflective color filter structure of the utility model is provided with an array of nanostructures on a substrate, and the nanostructures are arranged as two or more layers of metal nanostructures and dielectric nanostructures in an alternating stacking design. Through the plasma wave resonance effect between the metal nanostructures and the dielectric nanostructures, the structure can absorb light waves coupled with its surface plasma resonance frequency and reflect light waves in other bands, filtering light based on the color subtraction principle, thereby achieving filtering effects of different colors.

[0020] The duty ratio or period of the nanostructure of the reflective filter of the utility model corresponds to the complementary color light of the structure filtering wavelength. By adjusting its duty ratio or period, a variety of colors from yellow to cyan can be achieved, and it has the characteristics of a wide color gamut.

[0021] The reflective filter of the utility model has a narrow reflection spectrum, a half-peak width of only 50 nanometers, a high saturation, and produces brighter colors; and the reflection efficiency of the reflection valley of the structure is very low, which greatly improves the utilization rate of light energy. The reflectivity of the reflected light can be close to 0, and its complementary color brightness is high, which can make the light and dark contrast between colors more obvious.

[0022] The reflective filter of the utility model has good angular tolerance. When the incident angle varies from 0 to 60 degrees, the position of the reflection valley does not change much, that is, the color observed by the human eye remains basically unchanged, which solves the problem of angle sensitivity during the existing micro-nano structure filtering. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the reflective color filter structure of the utility model;

[0024] Figure 2 is a graph showing the relationship between the reflection efficiency and the incident angle of the filter structure of Example 1;

[0025] Figure 3 is a graph showing the relationship between the reflection efficiency and the duty ratio of the filter structure of Example 2;

[0026] Figure 4is a graph showing the relationship between the reflection efficiency and the period of the filter structure of Example 3;

[0027] Figure 5 The color spectrum displayed by the filter structure of Example 3 at different periods;

[0028] Figure 6 is a graph showing the relationship between the reflection efficiency of the filter structure and the thickness of the metal nanostructure in Example 4;

[0029] Figure 7 is a graph showing the relationship between the reflection efficiency of the filter structure and the thickness of the dielectric nanostructure in Example 5;

[0030] Figure 8 is a graph showing the relationship between the reflection efficiency and the incident angle of the filter structure of Example 6;

[0031] Figure 9 is a graph showing the relationship between the reflection efficiency and the duty ratio of the filter structure of Example 7;

[0032] Figure 10 is a graph showing the relationship between the reflection efficiency and array period of the filter structure of Example 8;

[0033] Figure 11 is a graph showing the relationship between the reflection efficiency of the filter structure and the thickness of the metal nanostructure in Example 9;

[0034] Figure 12 is a graph showing the relationship between the reflection efficiency of the filter structure and the thickness of the dielectric nanostructure in Example 10;

[0035] Figure 13 is a graph showing the relationship between the reflection efficiency of the filter structure of Example 11 and the number of nanostructure layers;

[0036] Figure 14 This is the electric field diagram of the filter structure of Example 1 at a specific wavelength of 535nm;

[0037] Explanation of the numbers in the figure: 1. substrate, 2. metal nanostructure, 3. dielectric nanostructure. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0039] This embodiment provides a reflective color filter structure, such as Figure 1As shown, it includes a substrate 1, on which a plurality of nanostructures distributed in an array are arranged, wherein the nanostructures include more than two layers of metal nanostructures 2 and more than two layers of dielectric nanostructures 3, wherein the metal nanostructures 2 and dielectric nanostructures 3 are alternately stacked from bottom to top, and the top and bottom layers of the nanostructures are both metal nanostructures 2.

[0040] As a specific embodiment, the thickness of the metal nanostructure 2 is 30-50nm, the thickness of the dielectric nanostructure 3 is 20-60nm, the duty ratio of the nanostructure is 0.25-0.35, and by adjusting the duty ratio, a variety of color transitions from yellow to cyan can be achieved, with a wide color gamut. The period of the nanostructure array arrangement is 100-300nm.

[0041] As a specific embodiment, the substrate 1 is made of a highly reflective metal, and its thickness is greater than the skin depth, and it mainly acts as a reflector. The specific material can be one or more of aluminum, silver, nickel, germanium, or other highly reflective metals; the material of the metal nanostructure 2 is aluminum and / or silver; the material of the dielectric nanostructure 3 is a high-reflectivity material, specifically one or more of gallium arsenide, iron oxide, gallium nitride, zinc sulfide, titanium dioxide, or other high-reflectivity dielectric materials.

[0042] As a specific embodiment, the cross-sectional distribution of all the nanostructures is in the shape of a grating, a square array, a rectangular array, a circular array or an elliptical array.

[0043] The following are specific embodiments

[0044] Example 1

[0045] This embodiment provides a reflective color filter structure comprising a substrate 1 on which are disposed a plurality of nanostructures arranged in an array. The nanostructures comprise three layers of metal nanostructures 2 and two layers of dielectric nanostructures 3. The metal nanostructures 2 and dielectric nanostructures 3 are alternately stacked from bottom to top, with both the top and bottom layers of the nanostructures being metal nanostructures 2. The substrate 1 is made of a metal material, specifically aluminum; the metal nanostructures 2 are made of highly reflective aluminum; the lower layer of dielectric nanostructures 3 have a refractive index of 3.3, while the upper layer has a refractive index of 3.5. The nanostructure array is a square array with a period of px = py = p = 180 nanometers in both the x and y directions, and a duty cycle F = 0.3. The metal nanostructures 2 are 40 nanometers thick, and the dielectric nanostructures 3 are 50 nanometers thick.

[0046] TM polarized light is incident on the top of this structure, and the incident angle of the light (reference Figure 1The filter's reflection characteristics and angular tolerance were analyzed using rigorous coupled wave theory (RCWA) with the incident angle (θ) varying from 0 to 75 degrees. Because the metal layer is a highly reflective material and its thickness exceeds the metal's skin depth, the transmittance is almost zero. Therefore, the structure exhibits primarily reflection and absorption characteristics. Due to surface plasmon resonance coupling between the multilayer nanostructures, some light is reflected, while others are absorbed.

[0047] Figure 2 The following graph shows the relationship between the reflection efficiency of the filter structure and the incident angle of this embodiment. When the incident angle varies from 0 to 75 degrees, the reflection peak and valley remain around 530 nanometers, and the reflection efficiency is close to zero. It can be assumed that the color of the reflected light hardly changes with the incident angle. In other words, this structure remains unchanged within the viewing angle range of 0 to 75 degrees, demonstrating good angular tolerance.

[0048] Example 2

[0049] The difference between this embodiment and embodiment 1 is that different duty ratios are set to study the effect of the duty ratio on the filtering performance. The other steps are consistent with the embodiment.

[0050] Figure 3 The following graph shows the relationship between the reflection efficiency of the filter structure and different duty ratios. It can be seen that the duty ratio F has a significant impact on the structure's reflection efficiency: when F varies between 0.25 and 0.35, the position of the reflection valley changes. As F increases, the reflection valley position redshifts, with the reflection peak changing from 460 nanometers to 608 nanometers, and the reflection efficiency changing from 0.0038 to 0.1752. When the duty ratio is 0.3, the reflection valley appears at 534 nanometers, and the reflection efficiency approaches zero. In other words, a duty ratio of 0.3 achieves optimal filtering performance.

[0051] Example 3

[0052] The difference between this embodiment and embodiment 1 is that different array periods are set to study the influence of the array period on the filtering performance, and the other steps are consistent with the embodiment.

[0053] Figure 4 The graph below shows the relationship between the reflection efficiency and period of the filter structure. It can be seen that when p varies between 150 nm and 220 nm, the position of the reflection valley changes, and as the wavelength increases, the position of the reflection valley redshifts. In other words, by controlling different periods, the wavelength of the filtered light will change, and the human eye will observe different colors. Based on this characteristic, as long as multi-layer nanostructures with different periods are designed on different pixels of the filter device, a color filter effect can be achieved, as shown in Fig. Figure 5 , it can be seen that this structure can achieve multiple colors and has the characteristics of wide color gamut.

[0054] Example 4

[0055] The difference between this embodiment and embodiment 1 is that metal nanostructures of different thicknesses are provided to study the effect of the thickness of the metal nanostructures on the filtering performance. The other steps are consistent with the embodiment.

[0056] Figure 6 The following graph shows the relationship between the filter structure's reflection efficiency and the thickness of the metal nanostructure. It can be seen that varying metal nanostructure thickness has a certain influence on the reflection peaks and valleys. As the thickness varies from 30 to 50 nanometers, the reflection peak shifts from 532 to 538 nanometers, and the reflection efficiency of the reflection valley changes from 0.0002 to 0.0312, both of which are relatively low. At a thickness of 40 nanometers, the reflection valley appears at 534 nanometers, with the reflection efficiency approaching zero, indicating optimal performance.

[0057] Example 5

[0058] The difference between this embodiment and embodiment 1 is that dielectric nanostructures of different thicknesses are provided to study the effect of the thickness of the dielectric nanostructures on the filtering performance. The other steps are consistent with those of the embodiment.

[0059] Figure 7 The graph shows the relationship between the filter structure's reflection efficiency and the thickness of the dielectric nanostructure. As can be seen, when the dielectric nanostructure thickness varies between 40 and 60 nanometers, the peak value of the reflection valley changes, from 530 to 544 nanometers, and the reflection efficiency of the valley changes from 0.0002 to 0.0630, indicating low reflection efficiency. The peak value of the reflection valley approaches zero, achieving optimal results, when the dielectric nanostructure thickness reaches 50 nanometers.

[0060] Example 6

[0061] The difference between this embodiment and embodiment 1 is that the nanostructure array is a cylindrical array, and the other steps are consistent with the embodiment.

[0062] Figure 8 The following graph shows the relationship between the reflection efficiency of the filter structure and the incident angle. As can be seen, when the incident angle varies from 0 to 75 degrees, the reflection peak and valley remain around 530 nanometers. This indicates that the color of the reflected light remains relatively stable as the incident angle changes. This means that the structure maintains similar reflection characteristics at different incident angles, demonstrating good angular tolerance.

[0063] Example 7

[0064] The difference between this embodiment and embodiment 6 is that different duty ratios are set to study the effect of the duty ratio on the filtering performance, and the other steps are consistent with the embodiment.

[0065] Figure 9The figure below shows the relationship between the reflection efficiency and duty cycle of the filter structure. It can be seen that the duty cycle has a significant impact on the structure's reflection efficiency. When F varies between 0.25 and 0.35, the position of the reflection valley changes significantly. As F increases, the reflection peak and valley shift from 475 nanometers to 615 nanometers, and the reflection efficiency changes from 0.0024 to 0.0352. When the duty cycle is 0.3, the reflection valley appears at 544 nanometers, and the reflection efficiency is approximately 0, achieving optimal results. It can be seen that by adjusting the duty cycle, the characteristics of the reflected light, including its wavelength position and reflection intensity, can be effectively controlled.

[0066] Example 8

[0067] The difference between this embodiment and embodiment 6 is that different array periods are set to study the influence of the array period on the filtering performance. The other steps are consistent with the embodiment.

[0068] Figure 10 This graph shows the relationship between the reflection efficiency of the filter structure and the array period. As can be seen, as p varies between 150 and 220 nanometers, the reflection valley position redshifts. This means that by precisely controlling the period, the wavelength of reflected light can be adjusted, resulting in different colors perceived by the human eye. By designing nanostructures with varying periods on different pixels in the filter, selective reflection of specific wavelengths is achieved, resulting in different perceived colors.

[0069] Example 9

[0070] The difference between this embodiment and embodiment 6 is that metal nanostructures of different thicknesses are provided to study the effect of the thickness of the metal nanostructures on the filtering performance. The other steps are consistent with the embodiment.

[0071] Figure 11 The following graph shows the relationship between the filter structure's reflective efficiency and the thickness of the metal nanostructures. It can be seen that varying the height of the metal nanostructures has a certain influence on the reflective peaks and valleys. As the metal nanostructure height varies from 30 nanometers to 50 nanometers, the reflective peaks and valleys vary between 0% and 2%. When the metal nanostructure height is set to 40 nanometers, the reflective valley occurs at 534 nanometers, at which point the reflective efficiency drops to almost zero. By finely adjusting the height of the metal nanostructures, the filter's reflective properties can be effectively controlled, achieving efficient reflection suppression of specific wavelengths of light, significantly enhancing light energy utilization.

[0072] Example 10

[0073] The difference between this embodiment and embodiment 6 is that dielectric nanostructures of different thicknesses are provided to study the effect of the thickness of the dielectric nanostructures on the filtering performance. The other steps are consistent with those of the embodiment.

[0074] Figure 12The graph shows the relationship between the filter structure's reflection efficiency and the dielectric nanostructure thickness. As can be seen, when the dielectric nanostructure height varies between 40 and 60 nanometers, the peak value of the reflection valley changes, from 540 nanometers to 556 nanometers, and the reflection efficiency decreases from 0.0038 to 0.0787, all with relatively low reflectivity. Comparing the peak values ​​of the reflection valleys at different dielectric nanostructure heights reveals that the reflection efficiency reaches its lowest point, 0.0038, when the dielectric grating height is set to 0.05 μm, indicating optimal reflection efficiency at this point.

[0075] Example 11

[0076] This embodiment differs from Example 1 in that different numbers of metal nanostructures and dielectric nanostructures are provided. Considering Example 1 as Scheme A, Scheme B provides two layers of metal nanostructures on a substrate, with a dielectric nanostructure layer between them. Scheme C provides a dielectric nanostructure layer above the substrate, with a metal nanostructure layer above it.

[0077] Figure 13 The relationship between the reflection efficiency of the filter structure and the number of nanostructure layers is shown in FIG. As solution A, Example 1 has a narrower reflection spectrum, a lower half-peak width of only 50 nanometers, a high saturation, and produces brighter colors. Solutions B and C have poorer effects.

[0078] Test Case

[0079] Figure 14 This is the electric field diagram of the filter structure of Example 1 at a specific wavelength of 535nm. It can be seen that the thickness of the metal layer is greater than the skin depth of the metal, resulting in almost zero transmittance. Furthermore, due to surface plasmon resonance coupling between the multilayer nanostructures, some light is reflected and some is absorbed. The electric field localized between the metal nanostructure layer and the dielectric nanostructure layer exhibits localized surface plasmon resonance.

[0080] The above-described embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. A reflective color filter structure, characterized in that: The invention comprises a substrate on which a plurality of nanostructures distributed in an array are arranged. The nanostructures include two or more layers of metal nanostructures and two or more layers of dielectric nanostructures. The metal nanostructures and dielectric nanostructures are alternately stacked from bottom to top, and the top and bottom layers of the nanostructures are both metal nanostructures.

2. The reflective color filter structure according to claim 1, wherein: The thickness of the metal nanostructure is 30-50 nm.

3. The reflective color filter structure according to claim 1, wherein: The thickness of the dielectric nanostructure is 20-60 nm.

4. The reflective color filter structure according to claim 1, wherein: The duty ratio of the nanostructure is 0.25-0.

35.

5. The reflective color filter structure according to claim 1, wherein: The period of the arrangement of the nanostructure array is 100-300 nm.

6. The reflective color filter structure according to claim 1, wherein: The substrate material is one or more of aluminum, silver, nickel, and germanium.

7. The reflective color filter structure according to claim 1, wherein: The material of the metal nanostructure is aluminum and / or silver.

8. The reflective color filter structure according to claim 1, wherein: The material of the dielectric nanostructure is one or more of gallium arsenide, iron oxide, gallium nitride, zinc sulfide, and titanium dioxide.

9. The reflective color filter structure according to claim 1, wherein: The number of layers of the metal nanostructure is three, and the number of layers of the dielectric nanostructure is two.

10. The reflective color filter structure according to claim 1, wherein: The cross-sectional distribution of the nanostructures is in the shape of a grating, a square array, a rectangular array, a circular array or an elliptical array.

Images