Ultra-broadband THz Emission from One- and Two-Color Laser-Induced Microplasmas at High Repetition Rate

We report on the generation of intense and broadband THz radiation from laser-induced microplasmas in air, driven by femtosecond fiber lasers operating at high repetition rates. We investigate both one-color and two-color plasma generation schemes. In the one-color case, we examine the angular emission pattern and spectral content of the THz radiation as a function of the laser focusing geometry. In the two-color configuration, we demonstrate efficient THz generation with a spectral content extending up to 30 THz using a compact Yb-doped fiber femtosecond laser system with a repetition rate of 200 kHz. These results offer a promising path toward practical implementation of plasma-based THz sources for broadband spectroscopy.