Impact of the pump wavelength in THz emissions by two-color femtosecond laser filaments in air

Laser filamentation is actively studied for its rich variety of applications, from supercontinuum generation to lightning control [1]. In air, femtosecond filaments result from the self-focusing of ultrashort light pulses that couple to their own plasma channel and stay self-guided upon extended paths at high intensity levels. Driven by strong nonlinearities, these optical structures are able to promote broadband THz-to-far-infrared radiation when using laser fields composed of two colors, e.g., a fundamental and its second harmonic [2].