Influence of a Fundamental Frequency Pulse Chirp on the Spectral and Temporal Second-Harmonic Characteristics

Abstract

The results of investigation of the possibility of reducing the duration of the second-harmonic radiation pulse generated by the starting complex of an THL-100 laser system by conversion of a pre-chirped fundamental frequency pulse are presented. A front-end compressor of the complex is used to obtain a fundamental harmonic pulse chirp at a central wavelength of 950 nm with duration of 70 fs. It is shown that a small excess of the group velocity dispersion (±3200–4000 fs2) of fundamental frequency radiation increases the width of the second-harmonic radiation spectrum by a factor of 1.5–2. A compensation for the excess dispersion of radiation pulses with broadened spectrum makes it possible to reduce the second-harmonic radiation pulse duration approximately proportionally to its spectral broadening and to obtain a minimal pulse duration of 35 fs.