Resonantly enhanced terahertz four-wave mixing in fluorides

Abstract

Converting a THz signal into the optical domain is of great interest for THz sensing and spectroscopy. Here intense broadband THz pulses with a central frequency of Ω THz are mixed with an optical pump at ω p , and a signal is observed at a wavelength of ω s = 2(ω p - Δω p ) - Ω THz with the detuning ω p - Δω p being due to pump pulse spectral broadening. The observed THz-four-wave mixing (FWM) signal close to 400 nm is shown to result from a resonantly amplified four-wave mixing in CaF2, BaF2, and MgF2.