Efficient nonlinear pulse compression to 20 fs based on an all-solid-state periodic self-focusing system

Abstract

Ultrafast lasers with high average power and excellent spatial characteristics have been sought after in the ultrafast optics field. In this work, we propose and experimentally demonstrate a simple Gaussian beam optics model to realize the configuration of periodic self-focusing systems for generating intense ultrashort pulse with high spatial quality. An efficient 17-fold nonlinear pulse compression is implemented by a two-stage solid-thin-plates periodic self-focusing system based on this model, delivering 20 fs (full-width-at-half-maximum, FWHM) pulses with a pulse energy of 155 µJ at a repetition rate of 200 kHz. The waveguide-like self-consistent stationary spatial mode propagation achieved in the system enables the high efficiency of 94 %, good beam quality and spectral homogeneity across the beam profile. The solid-thin-plates in three different materials are used in the first stage, which manifests the model can be widely applied in many kinds of nonlinear medium. In the second stage, a simple and compact double-pass architecture is demonstrated, indirectly proving the accuracy of model. The beam propagations under non-stationary modes are also investigated and a more precise quasi-stable oscillatory region is suggested based on the Gaussian beam optics model. These results underline that the Gaussian beam optics model is a practical solution for identifying the self-consistent stationary mode of the periodic self-focusing system and show the potential of the periodic self-focusing system for efficient few-cycle pulses generation which is demand by many applications.