Studies on nonlinear pulse compression technique based on multi-pass in plano-cancave cavity

Ultrafast femtosecond laser systems with hundreds of microjoules of energy operating at repetition frequencies of several kilohertz have very important applications for many fields such as medicine,mid-infrared laser generation,industrial processing and vibrational spectroscopy.The Chirped Pulse Amplification (CPA) technique provides a feasible path to obtain light sources with such parameters.However,the use of chirped pulse amplification increases the technical complexity and cost of the laser system.Recently,the proposal of Multi-pass Cell (MPC) nonlinear pulse compression technique allows us to obtain high power ultrafast femtosecond pulses with reduced technical complexity and cost.The composition of the device requires only two concave mirrors and a nonlinear medium in between.In the past seven years,the Multi-pass Cell nonlinear pulse compression technique has been developed so much that it has become possible to obtain ultrashort pulses with average power of more than a few kW and peak power of tens to hundreds of TW.In this work,we have achieved nonlinear pulse compression for a 100 W picosecond laser using an improved nonlinear pulse compression scheme that combines a hybrid of a plano-cancave multi-pass cell and multi-thin-plate.Using fused silica plates in plano-cancave cavity,the spectral bandwidth (FWHM) of input picosecond laser is broadened from 0.24 nm to 4.8 nm due to self-phase modulation effect,the pulse is compressed to 483 fs by dispersion compensation using grating pairs,which corresponds the compression factor of 22,and the final output power of 44.2 W is obtained.As comparison of conventional MPC,the plano-cancave cavity scheme we developed is a very promising solution for nonlinear compression due to its compact,more stability and large compression ratio.