Spectral phase aberration and its influence on pulse compression in an actively modulated ultrafast laser system

Abstract

In actively modulated laser systems such as the time-lens source, quadratic temporal phase modulation was naturally considered as the “ideal” modulation. However, it is unknown that whether a quadratic temporal phase modulation (equivalently, a linear chirp) translates into a quadratic spectral phase modulation, which can be easily eliminated using compressors. Here we study this phase transfer both analytically and numerically. Our results indicate that non-quadratic spectral phase aberration arises even if the temporal phase modulation is quadratic. Consequently, there is observable difference between the compressed pulses with a flat spectral phase and with quadratic spectral phase compensation only. However, as quadratic temporal phase modulation increases, non-quadratic spectral phase modulation decreases, and pulse compression with quadratic spectral phase tends to that with a flat spectral phase.