Terahertz emission and energy reservoir of air-plasma filamentation induced by two-color femtosecond laser pulses

Abstract

Terahertz (THz) emission along air-plasma filamentation induced by two-color laser pulses is detected with a moving metal wafer with a 200μm pinhole. It is found that the THz emission changes along the filamentation slowly when the pump laser pulses are focused perfectly. Although the energy reservoir of filamentation contains half energy of laser pulse, most of THz pulse energy is in air-plasma. If the lens used focusing the pump lasers is tilted, the filamentation becomes longer and the THz emission changes more slowly along the filamentation, while their spectra have the same profile.