Dynamically tunable, single pixel full-color plasmonic display, method and applications
View Patent ↗Dynamic, color-changing surfaces have many applications including but not limited to displays, wearables, and active camouflage. Plasmonic nanostructures can fill this role with the advantages of ultra-small pixels, high reflectivity, and post-fabrication tuning through control of the surrounding media. However, while post-fabrication tuning have yet to cover a full red-green-blue (RGB) color basis set with a single nanostructure of singular dimensions, the present invention contemplates a novel LC-based apparatus and methods that enable such tuning and demonstrates a liquid crystal-plasmonic system that covers the full red/green/blue (RGB) color basis set, as a function only of voltage. This is accomplished through a surface morphology-induced, polarization dependent, plasmonic resonance and a combination of bulk and surface liquid crystal effects that manifest at different voltages. The resulting LC-plasmonic system provides an unprecedented color range for a single plasmonic nanostructure, eliminating the need for the three spatially static sub-pixels of current displays. The system's compatibility with existing LCD technology is possible by integrating it with a commercially available thin-film-transistor (TFT) array. The imprinted surface readily interfaces with computers to display images as well as video.
1. A liquid crystal-plasmonic display apparatus, comprising:
a linear polarizer;
a superstrate;
a transparent electrode;
a rubbed polyimide film;
a liquid crystal (LC); and
a nano-structured plasmonic surface disposed on a substrate,
where the transparent electrode is disposed to apply an electric field across the liquid crystal, and the rubbed polyimide aligns the LC parallel to the axis it is rubbed to provide homogeneous alignment,
wherein the LC orientation near the plasmonic surface determines the effective refractive index of polarization-sensitive, grating-coupled surface plasmon (GCSP) modes and,
therefore, the resonant wavelength of the nano-structured plasmonic surface,
further wherein the apparatus is characterized by a reflective color changing surface capable of producing the full RGB color basis set, all as a function only of voltage and based on a single nanostructure.
2. The apparatus of claim 1 , wherein the nano-structured plasmonic surface is a rough surface, inducing polarization dependence on the GSCP resonance in the presence of an anistropic media.
3. The apparatus of claim 1 , wherein the nano-structured plasmonic surface is a smooth surface, resulting in substantial polarization independence.
4. The apparatus of claim 1 , wherein the LC is a cell having at least a portion thereof comprised of the nano-structured plasmonic surface.
5. The apparatus of claim 1 , wherein the nano-structured plasmonic surface is a nano-structured aluminum surface.
6. The apparatus of claim 1 , wherein the superstrate is a glass composition.
7. The apparatus of claim 1 , wherein the transparent electrode comprises indium tin oxide (ITO).
8. The apparatus of claim 1 , further comprising a cell gap of the LC measuring approximately 8.5 μm.
9. A method of displaying a tunable color image, comprising:
providing the liquid crystal-plasmonic display apparatus of claim 1 ;
transmitting incident unpolarized ambient light through the linear polarizer, the superstrate, the transparent electrode, and the rubbed polyimide film, wherein the incident unpolarized light becomes polarized, passes through the LC, and excites grating coupled surface plasmons (GSCP) on the nanostructured surface;
applying a voltage across the plasmonic surface and the transparent electrode, thereby controlling the orientation of the LC throughout the cell; and
varying the voltage between a low and a high range.
10. The method of claim 9 , further comprising the step of adjusting the angle of the linear polarizer in relation to the LC.
11. The method of claim 9 , further comprising the step of aligning the linear polarizer parallel to the LC.
12. The method of claim 11 , further comprising the step of reflecting a blue color from the liquid crystal-plasmonic display apparatus.
13. The method of claim 9 , further comprising the step of aligning the linear polarizer perpendicular to the LC.
14. The method of claim 13 , further comprising the step of reflecting red color from the liquid crystal-plasmonic display apparatus.
15. The method of claim 9 , wherein the nano-structured plasmonic surface is a nano-structured aluminum surface.
16. The method of claim 9 , wherein the superstrate is a glass composition.
17. The method of claim 9 , wherein the transparent electrode comprises indium tin oxide (ITO).