US 12,248,204 B1
Broadband polarization rotator and optical switch
Gary D. Sharp, Boulder, CO (US); and David Coleman, Louisville, CO (US)
Assigned to Meta Platform Technologies, LLC, Menlo Park, CA (US)
Filed by Meta Platforms Technologies, LLC, Menlo Park, CA (US)
Filed on May 1, 2023, as Appl. No. 18/141,972.
Int. Cl. G02F 1/13363 (2006.01); G02F 1/01 (2006.01); G02F 1/1335 (2006.01); G02F 1/139 (2006.01); G06F 1/16 (2006.01); G02B 27/01 (2006.01)
CPC G02F 1/0136 (2013.01) [G02F 1/133553 (2013.01); G02F 1/133616 (2021.01); G02F 1/13363 (2013.01); G02F 1/1398 (2021.01); G06F 1/163 (2013.01); G02B 27/0172 (2013.01); G02F 2203/02 (2013.01); G02F 2413/07 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A passive compensation structure (PCS) for a liquid crystal (LC) layer switchable between an undriven state corresponding to a twisted LC director configuration and a driven state corresponding to a substantially vertical LC director configuration, wherein the LC layer is configured to rotate, when the LC layer is in the undriven state, an achromatic polarization state of a light beam orthogonally upon completion of a double pass of the light beam through the LC layer, the PCS comprising:
a stack of fixed-retardation layers configured to rotate, when the LC layer is in the undriven state, the achromatic polarization state of the light beam orthogonally upon completion of a double pass of the light beam through the PCS such that the achromatic polarization state of the light beam received by the PCS and the achromatic polarization state of the light beam exiting the PCS are orthogonal to one another.