Third-Harmonic Generation in a Plasma of Self-Induced Optical Breakdown in Air Using 80-fs Laser Pulses: Self-Action of Light Beams and Spectral Broadening

Abstract

Recently, much attention has been focused on the generation of high-order harmonics using high-power laser pulses. Optical harmonics of extremely high orders were detected in experiments using high-power ultrashort laser pulses focused into rare-gas jets [1 - 4]. For the most part, experiments on harmonic generation both in rare gases [1 - 4] and in a laser-produced plasma [5 - 12] use pulsed high-power systems. First experiments on third-harmonic generation at a high repetition rate, which used 1-kHz laser pulses with a duration of 200 fs, demonstrated that the efficiency of third-harmonic generation (THG) in a plasma of self-induced optical breakdown can be as high as 7*10-4 [13].