Enhancement of terahertz emission during single-color filamentation by chirping laser pulse

An experimental study of laser pulse duration influence on the terahertz emission during single-color filamentation is carried out. It is shown that for each terahertz frequency there is an optimal laser pulse duration providing maximal generation at constant pulse energy. It is demonstrated that longer pulses are required for stronger low-frequency terahertz emission, thus despite considerable laser peak power decreasing the terahertz radiation yield can be increased by more than 3 times.