Generation of terahertz radiation in thin vanadium dioxide films undergoing metal-insulator phase transition

摘要

Generation of terahertz (THz) radiation was observed in epitaxial VO films grown on R- and C-cut sapphire substrates above and below the metal-insulator phase transition temperature. Polarization analysis of the emitted THz radiation reveals strong in-plane anisotropy of the conductive phase of VO which is not observed for insulating phase, generation efficiency increases up to 30 times after phase transition. Properties of generated THz radiation in VO are defined by the displacement photocurrent at the film-air and film-substrate interfaces.