Stretchable polarization conversion structure colored light switch

Abstract

The invention provides a stretchable polarization conversion structure colored light switch. The device is composed of a periodic structure, a PDMS substrate 1, two GaN nano-columns 2 and 4, a SiO2 nano-column 3 and a PDMS dielectric layer 5 are sequentially included in one period from bottom to top, and a GaN-SiO2-GaN sandwich structure is located in the center of the substrate to form a sandwich structure. The manufacturing process is mature, the material cost is low, and the designed optical switch can realize optical switch and polarization conversion structural color under mechanical tuning. A single reflection peak with the bandwidth smaller than 7 nm is achieved in the visible light wave band, the reflection efficiency reaches up to 99%, and polarization conversion is achieved by controlling the polarization direction of incident light. In addition, wide color gamut modulation is realized by stretching the substrate and changing the geometric parameter size at the same time, and the result covers near 210 nm visible spectrum. Therefore, the metasurface can be applied to the fields of new-generation display technology, optical encryption and the like, and can also be used for researching stretchable and wearable photonics.

Description

(I) Technical field

[0001] The present invention relates to a stretchable polarization conversion structural color optical switch. This metasurface can be applied to fields such as new generation display technology and optical encryption, and can also be used to study stretchable and wearable photonics. (II) Background technology

[0002] As an important part of vision, color has been studied since ancient times. Traditional dyes and pigments cannot be used in micro-nano devices due to size limitations. In recent years, artificial metasurface structural colors inspired by nature have attracted attention. Due to its advantages such as controllable size and high resolution, it is widely used in printing and anti-counterfeiting. Traditional metasurfaces are mostly made of metal, but the color saturation is low due to Ohmic loss. To solve this problem, researchers have developed low-loss, high-refractive-index all-dielectric metasurfaces such as Si, TiO2, and GaN. In particular, GaN has great application potential due to its low loss, low cost, ability to produce high-saturation colors and wide color gamut, and sensitivity to light polarization. With the growing demand for photonic technology, researchers have proposed a polarization-converting structural color that can achieve color switching without changing the geometry or material, which is suitable for high-density optical data storage. However, the optical properties of most nanostructures are static, which limits their applications. Researchers have developed a tunable metasurface using a flexible polymer PDMS substrate that allows mechanical deformation, achieves fast and repeatable tuning, and has programmable and reconfigurable properties. Although GaN and PDMS each have their own advantages, there is currently relatively limited research on combining these two excellent materials on metasurfaces. Therefore, integrating GaN and PDMS in tunable metasurfaces offers unlimited possibilities for developing new and advanced photonic devices, and further research in this area may lead to exciting advances and new applications in the field of photonics.

[0003] However, there are relatively few studies in this field, and its color gamut is quite limited. Therefore, in order to overcome the shortcomings of the extremely low quality factor, small working bandwidth, and limited tunability of the metasurface, and based on the above research, this paper proposes a stretchable polarization conversion structural color optical switch. The metasurface is actively switched between the "on" and "off" states by stretching the flexible substrate and changing the polarization angle. And finally, by further optimizing the structure, a highly saturated polarization conversion structural color is achieved. With the rapid and widespread development of new nanofabrication technologies, reconfigurable metasurfaces based on micromechanical stretching and tuning technology have great development potential in fields such as optical encryption. (III) Summary of the invention

[0004] The present invention designs a stretchable polarization conversion structural color optical switch, which can realize optical switching and polarization conversion structural color under mechanical tuning. A single reflection peak with a bandwidth of less than 7nm is realized in the visible light band, the reflection efficiency is as high as 99%, and polarization conversion is realized by controlling the polarization direction of the incident light. In addition, by simultaneously stretching the substrate and changing the size of the geometric parameters, wide color gamut modulation is achieved, and the result covers nearly 210nm of the visible spectrum.

[0005] The object of the present invention is achieved in that:

[0006] A stretchable polarization conversion structural color optical switch is a periodic structure, which includes a PDMS substrate 1, a GaN-SiO2-GaN sandwich structure and a PDMS dielectric layer 5 from bottom to top in one period. The GaN-SiO2-GaN sandwich structure includes two GaN nanocolumns 2 and 4 and one SiO2 nanocolumn 3, wherein the SiO2 nanocolumn is located in the center of the substrate, and the other two GaN nanocolumns are symmetrically distributed about the SiO2 nanocolumn. The top layer is a PDMS dielectric layer with thicknesses of h1, h2, and h3, respectively.

[0007] Preferably, the PDMS substrate has a thickness of h1, a length of Px=330 nm, and a length of Py=330 nm.

[0008] Preferably, the top layer is made of PDMS, with a thickness of h3, a length of w=240 nm, and a width of b=100 nm.

[0009] Preferably, the nanocolumns are made of GaN and SiO2, and have a thickness of h2, wherein the GaN nanocolumn has a length of a=100 nm and a width of b, and the SiO2 nanocolumn has a length of w-2*a and a width of b.

[0010] Since the present invention adopts the above technical solution, the design is simpler than other structural color devices. GaN, SiO2 and PDMS are selected as the all-dielectric material, which has lower Joule loss and higher sensitivity than other materials. The excited color is brighter, the manufacturing cost is lower, and it is more widely used in practical applications. (IV) Description of the drawings

[0011] Figure 1 This is a schematic diagram of the three-dimensional structure of a stretchable polarization-converting structural color optical switch.

[0012] Figure 2 are the reflection and transmission spectra of this structure, and it can be seen that polarization conversion is achieved.

[0013] Figure 3 It is the size design of the metasurface composed of this structure under different structural parameters.

[0014] Figure 4is x-polarized light in the CIE1931 color space Figure 5 The chromaticity coordinates of .

[0015] Figure 5 It is the reflection spectrum of the metasurface along x-polarization in the visible light band when changing different size parameters.

[0016] Figure 6 It is the reflection spectrum of the metasurface along the y-polarization in the visible light band when changing different size parameters. (V) Specific implementation methods

[0017] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in combination with specific examples and with reference to the accompanying drawings.

[0018] like Figure 1 As shown, the present invention proposes a stretchable polarization conversion structure color optical switch. The device is composed of a three-layer structure, the main structure includes a PDMS substrate 1, GaN nanocolumns 2 and 4, SiO2 nanocolumns 3 and a PDMS dielectric layer 5.

[0019] As an embodiment, there are two GaN nanocolumns and one SiO2 nanocolumn on a PDMS substrate, forming a sandwich structure, wherein the SiO2 nanocolumn is located in the center of the substrate, and the other two GaN nanocolumns are symmetrically distributed about the SiO2 nanocolumn, with thicknesses of h1, h2, and h3, respectively. The PDMS substrate has a thickness of h1, a length of Px = 330nm, and a length of Py = 330nm. The top layer is PDMS, with a thickness of h3, a length of w = 240nm, and a width of b = 100nm. The nanocolumns are made of GaN and SiO2, with a thickness of h2, wherein the GaN nanocolumn has a length of a = 100nm and a width of b, and the SiO2 nanocolumn has a length of w-2*a and a width of b.

[0021] The expression of the tristimulus value of the reflected color of the nanostructure unit calculated based on the reflection spectrum is as follows:

[0022]

[0023] The chromaticity coordinates obtained based on the tristimulus values ​​of the object are:

[0024]

[0025] The extinction ratio of the optical switch can be expressed by the formula Calculated.

[0026] The polarization conversion structure color optical switch implemented in this embodiment is as follows Figure 2As shown in the figure, the simulation results are obtained by simulating the structure using the three-dimensional finite difference time domain (FDTD) method. Through calculation, it can be seen that a reflection peak appears at 500.6nm in the reflection spectrum under x-polarized light, as high as 99%, which is considered to be the "on" state. In the reflection spectrum under y-polarized light, the reflectivity at 500.6nm is about 2%, which is considered to be the "off" state, and the extinction ratio is about 16.9dB.

[0027] Figure 3 It is the size design of the metasurface composed of this structure under different structural parameters.

[0028] Figure 4 is x-polarized light in CIE1931 color space Figure 3 A wide color gamut is achieved in the present invention.

[0029] Figure 5 When different size parameters are changed, the reflectance spectrum of the metasurface under x-polarized light in the visible light band covers nearly 210nm of the visible light spectrum and has a very high reflectivity (all above 99%).

[0030] Figure 6 When changing different size parameters, the reflectance spectrum of the metasurface under y-polarized light in the visible light band. Figure 5 Together, they demonstrated that the optical switch achieves the function of polarization-converting structural color.

[0031] It should be noted that although the embodiments of the present invention described above are illustrative, they are not intended to limit the present invention, and therefore the present invention is not limited to the above specific embodiments. Without departing from the principles of the present invention, any other embodiments obtained by those skilled in the art under the guidance of the present invention are deemed to be within the protection of the present invention.

Claims

1. A stretchable polarization conversion structural color optical switch. A period includes a PDMS substrate 1 and a GaN-SiO2-GaN sandwich structure from bottom to top. The GaN-SiO2-GaN sandwich structure includes two GaN nanocolumns 2 and 4 and one SiO2 nanocolumn 3, wherein the SiO2 nanocolumn is located in the center of the substrate, and the other two GaN nanocolumns are symmetrically distributed about the SiO2 nanocolumn. The top layer is a PDMS dielectric layer with thicknesses of h1, h2, and h3, respectively.

2. The stretchable polarization conversion structure color optical switch according to claim 1, characterized in that: The sandwich structure consists of two GaN nanocolumns, one SiO2 nanocolumn and a PDMS dielectric layer, and the substrate material is PDMS.

3. The stretchable polarization conversion structure color optical switch according to claim 1, characterized in that: The top layer is made of PDMS material with a thickness of h3, a length of w=240 nm, and a width of b=100 nm.

4. The stretchable polarization conversion structure color optical switch according to claim 1, characterized in that: The two nanorods are made of GaN material with a thickness of h2, a length of a=100 nm, and a width of b.

5. The stretchable polarization conversion structure color optical switch according to claim 1, characterized in that: A nanocolumn is made of silicon material, and its thickness is h2. The length of the SiO2 nanocolumn is w-2*a, and the width is b.

6. The stretchable polarization conversion structure color optical switch according to claim 1, characterized in that: The PDMS substrate has a thickness of h1, and a length of Px=330nm and Py=330nm.

7. The stretchable polarization conversion structure color optical switch according to claim 1, characterized in that: The designed optical switch can realize optical switching and polarization conversion structural color under mechanical tuning. A single reflection peak with a bandwidth of less than 7nm is achieved in the visible light band, the reflection efficiency is as high as 99%, and polarization conversion is achieved by controlling the polarization direction of the incident light.

8. The stretchable polarization conversion structure color optical switch according to claim 1, characterized in that: By simultaneously stretching the substrate and changing the geometric parameter dimensions, wide color gamut modulation is achieved, covering nearly 210nm of the visible spectrum.

Images