Polarization Control of Terahertz Spintronic Emitter Combined with Liquid Crystal by the External Magnetic and Electric Field

We demonstrate a polarization-tunable terahertz emitter that integrates a ferromagnetic heterostructure and large birefringence liquid crystals by the external magnetic and electric field. The direction of the magnetic field can control the emitted THz wave from linear to circular polarization. The phase retardation in liquid crystal layer between ordinary and extraordinary directions is continuously adjustable by the low-voltage electric field.