Phys.org  October 26, 2021 Researchers in China made laser-driven terahertz emitters, consisting of metasurface-patterned magnetic multilayer heterostructures that can overcome the shortcomings of the conventional approaches. They have demonstrated the efficient generation and manipulation of broadband chiral terahertz waves. The emitter’s ellipticity can reach >0.75 over a broad terahertz bandwidth (1 to 5 THz), it is an efficient source for few-cycle circularly polarized terahertz pulses with stable carrier waveforms, and has flexible control of ellipticity and helicity. They have shown that the terahertz polarization state is dictated by the interplay between laser-induced spintronic-origin currents and the screening charges/currents in the […]