Visible light band reflection metasurface device and reflected light wavelength modulation method

Patent metadata

Field	Value
Publication number	US-11092870-B2
Application number	US-201816073509-A
Country	US
Kind code	B2
Filing date	Jan 29, 2018
Priority date	Mar 6, 2017
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

A visible light band reflection metasurface device and a reflected light wavelength modulation method. The device successively includes, from top to bottom, a metal metasurface layer with periodically arranged antenna units, a modulation layer formed by an electro-optic material, a metal reflection layer and a substrate layer; the antenna unit period is less than the incident wavelength, and the thickness is greater than the skin depth of metal and less than 100 nm; the thickness of the modulation layer is less than the wavelength of the incident light; and the thickness of the metal reflection layer is greater than the skin depth of metal and less than the wavelength of the incident light; and an external voltage source can modulate the color of the reflected light, and can achieve voltage modulation of the color of reflected light in the visible light band.

First claim

What is claimed is:

1. A visible light band reflection metasurface device, wherein the device successively includes, from top to bottom:
a metal metasurface layer having a thickness with periodically arranged antenna units,
a modulation layer having a thickness formed of an electro-optic material,
a metal reflection layer having a thickness and
a substrate layer;
wherein an antenna unit period of the antenna units is less than a wavelength of incident light, and
wherein a thickness of the modulation layer is greater than a skin-effect depth of metal metasurface layer and less than 100 nm, the skin-effect is defined as a distance that the incident light penetrates into the metal metasurface layer;
the thickness of the modulation layer is less than the wavelength of the incident light; and
a thickness of the metal reflection layer is greater than the skin-effect depth of the metal metasurface layer surface and less than the wavelength of the incident light.

2. The visible light band reflective metasurface device according to claim 1 , wherein the metal metasurface layer is composed of periodically arranged antenna units with a protrusion structure or its Babinet-inverted structure or slot structure.

3. The visible light band reflection metasurface device according to claim 1 , wherein the antenna shape of the metal metasurface layer is a strip, a V shape, an H shape, a U shape, or a C shape.

4. The visible light band reflection metasurface device according to claim 1 , wherein materials of the metal metasurface layer and the metal reflection layer are gold, silver, aluminum, copper, gold-silver alloys, gold-aluminum alloys, gold-copper alloys, silver-aluminum alloys, silver-copper alloys or copper-aluminum alloys; and the substrate material is semiconductor material.

5. The visible light band reflective metasurface device according to claim 1 , wherein the modulation layer is formed of an electro-optic material operating in the visible light band and has an electro-optic coefficient with the order of magnitude being 1 nm/V; when the metal metasurface layer is an antenna protrusion structure, a refractive index of the electro-optic material is greater than or equal to 2; and when the metal metasurface layer is a metal slot structure, the refractive index of the electro-optic material is less than 2.

6. A reflected light wavelength modulation method based on the metasurface device according to claim 1 , including the following steps:
(1) judging whether the metal metasurface layer is a metal antenna the protrusion structure:
if the metal metasurface layer is the metal antenna protrusion structure, adding an ITO thin film layer on the upper side of the metal metasurface layer, and then executing step (2); if not, directly skipping to execute step (2);
(2) connecting a DC voltage source:
connecting a positive output end of the DC voltage source with the metal metasurface layer, and grounding a negative output end of the DC voltage source and the metal reflection layer together;
(3) modulating a reflection wavelength:
enabling an incident light to enter into the metasurface layer of the metasurface device, and adjusting the voltage of the DC voltage source to change the refractive index of the modulation layer, thereby changing the peak wavelength of cross-polarized reflected light.

7. The reflected light wavelength modulation method according to claim 6 , wherein the step (2) is specifically:
if the metal metasurface layer is the metal antenna protrusion structure, it is necessary to add a transparent ITO thin film on the surface of the metal metasurface layer for electric conduction; and the positive output end of the DC voltage source is connected with the transparent ITO thin film fitted on the metal metasurface layer, while the negative input end of the DC voltage source and the metal reflection layer are grounded together;
if the metal metasurface layer is the metal slot structure, the positive output end of the DC voltage source is connected with the metal metasurface layer, while the negative input end of the DC voltage source and the metal reflection layer are grounded together.

8. The reflected light wavelength modulation method according to claim 6 , wherein the incident light is linear polarized or circular polarized wave with wide waveband, and is vertically incident to the metal metasurface layer.

9. The reflected light wavelength modulation method according to claim 6 , wherein the reflected light is one beam of light waves, or two beams of light waves symmetrically distributed at both sides of the incident light wave.

10. The reflected light wavelength modulation method according to claim 6 , wherein an absolute value of the voltage of the DC voltage source is greater than or equal to 0 and less than V max , wherein V max is the breakdown voltage of metal metasurface layer-modulation layer-metal reflection layer.

Assignees

• Univ Southeast

Inventors

• Tu Yan
• Yang Lanlan
• Guo Jingjing
• Wang Lili
• Wang Baoping
• Zhang Yuning
• Zhong Xuefei

Classifications

• H01Q15/242

  Polarisation converters · CPC title

• H01Q15/0026

  said selective devices having a stacked geometry or having multiple layers · CPC title

• H01Q15/002

  said selective devices being reconfigurable or tunable, e.g. using switches or diodes · CPC title

• H01Q13/16

  Folded slot antennas · CPC title

• H01Q3/44

  varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element · CPC title