Magnetically and electrically polarization-tunable THz emitter with integrated ferromagnetic heterostructure and large-birefringence liquid crystal

A magnetically and electrically polarization-tunable terahertz emitter that integrates a ferromagnetic heterostrueture and targe-birefringence liquid crystals is demonstrated. The heterostrueture and the liquid crystal cell act as the broadband terahertz source and the phase retarder, respectively. The polarization state is switched between linear and circular by changing the direction of the external magnetic field. The phase retardation for frequencies higher than 1 THz is continuously adjustable over a range of pi/2 by applying a low voltage. This compact, broadband, economical, and easy-to-regulate terahertz emitter can be widely used in polarization-sensitive research and engineering applications. (C) 2018 The Japan Society of Applied Physics