US 12,216,376 B2
Metasurface-based active retroreflector
Sang-Yen Cho, Columbia, MD (US); and Weimin Zhou, Rockville, MD (US)
Assigned to The United States of America as represented by the Secretary of the Army, Washington, DC (US)
Filed by U.S. Army DEVCOM, Army Research Laboratory, Adelphi, MD (US)
Filed on Jan. 20, 2023, as Appl. No. 18/099,278.
Prior Publication US 2024/0248366 A1, Jul. 25, 2024
Int. Cl. G02F 1/19 (2019.01); H04B 10/11 (2013.01)
CPC G02F 1/19 (2013.01) [H04B 10/11 (2013.01); G02F 2202/30 (2013.01); G02F 2203/15 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A retroreflector apparatus for processing an optical beam incident thereon, comprising:
an upper metasurface separated from a lower metasurface by an optically transparent region therebetween, the optically transparent region configured to pass the incident optical beam between the upper metasurface and the lower metasurface;
the upper metasurface having a plurality of sub-wavelength scale resonators formed thereat, the upper metasurface configured to spatially modify a local phase of an optical beam passing therethrough to shape a wavefront thereof on a lower metasurface;
the lower metasurface disposed above a frequency-selective reflector and having a plurality of sub-wavelength scale resonators formed thereat, the lower metasurface configured to spatially modify a local phase of an optical beam passing therethrough to the reflector and to focus a reflected optical beam on the focal plane of the upper metasurface;
the upper metasurface configured, in response to an electric voltage imparted thereto, to spatially modify a local phase or a transmitted intensity of the reflected optical beam passing therethrough to provide a frequency-selective retroreflected optical beam.