Spectral control of terahertz radiation from inhomogeneous plasma filaments by tailoring two-color laser beams

Terahertz (THz) radiation from an inhomogeneous plasma filament generated by focusing two-color femtosecond laser pulses into argon gas filled in a chamber is investigated experimentally tailoring the Gaussian pump beams with iris, where broadband THz emission over 10 produced. It found that collected far-field includes not only coherent but also partial-coherent components of waves, which are emitted different parts densities, contributing correspondingly to frequencies spectrum. Our results suggest spectrum can be manipulated controlling density distribution filaments.