Generation of backward terahertz waves in GaSe crystals

摘要

We have observed a backward-propagating terahertz wave by mixing two coherent infrared beams in two GaSe crystals. For the 47 mm long crystal, the output wavelength can be tuned in the wide range of 167.6 to 2060 (mu)m (0.146 to 1.79 THz), whereas the output peak power reaches 217 W. The corresponding power conversion efficiency is approx0.03percent.