Abstract-Unipolar terahertz pulse formation in a nonequilibrium plasma channel formed by an ultrashort uv laser pulse

 

A. V. Bogatskaya, E. A. Volkova, and A. M. Popov

https://journals.aps.org/pre/accepted/68079Ya4M4c1f87fb0f414c03bb165b37d200c24a

We performed the new approach to produce highly unipolar terahertz pulses. The idea is based on the nonuniform amplification of seed ultrashort CEP pulses in nonequilibrium fast relaxing plasma of air or nitrogen. If the gain coefficient drops significantly within the duration of one-cycle CEP pulse, it undergoes significant distortion where the leading edge of the pulse is amplified and the trailing tail of opposite polarity is absorbed. The obtained results involve self-consistent solution of second-order wave equation and kinetic Boltz-mann equation for the electron velocity distribution function relaxation.