Multi-mW-level, air-plasma induced ultra-broadband THz pulses for nonlinear THz spectroscopy

Abstract

Two-color fs laser-induced air-plasma enables generation of THz pulses with extremely large bandwidth. In recent years, significant progress has been made on improving THz generation efficiency from such a process, including adoption of cylindrical lens focusing [1] , multiple-color (harmonic) mixing [2] , and long wavelength pumping [3] , etc. Very recently, with a 30-mJ, 3.9-µm, 20-Hz pump laser, THz yield as high as 185 µJ (3.7 mW) has been reported [4] . However, with the more accessible 1-kHz commercial OPA as the long wavelength pumping source, the reported THz yield was 0.6 mW [3] . In this abstract, we present highest THz yield from a standard kHz OPA driving source – THz generation at multi-mW-level. We also show the huge potential of such THz source by demonstrating strong nonlinear transmission in a n-doped SiC sample.