Magnetically tunable room-temperature 2 pi liquid crystal terahertz phase shifter

Abstract

Tunable phase shift up to 360 degrees at 1 THz is achieved with a liquid crystal (LC) device. The key to this design is (1) the use of a nematic LC, E7, which exhibits a birefringence of ~ 0.17 (0.2 - 1.2 THz); (2) a LC cell (3-mm in thickness) with sandwiched structure to increase the interaction length while minimizing interface Fresnel losses; and (3) the use of magnetic field to align the thick LC cell and achieve continuous tuning of phase from 0 to 360 degrees . This device can be operated over a broad range near room temperature.