Generation of 71.3W femtosecond laser by pulse nonlinear compression

Abstract

The power scale of femtosecond lasers based on Ti:sapphire or Yb-doped gain media has reached a high level by the using of chirped pulse amplification. The dispersive elements are normally employed in CPA devices, which increases the complexity and cost of the laser system. However, for the Nd-doped laser can be amplified to hundreds of microjoules or even several millijoules directly without CPA technology. So compressing the picosecond pulse to obtain femtosecond laser pulses with hundreds of microjoules pulse energy by post-compression technology becomes meaningful work. The pulse post-compression technology is the combining of nonlinear spectral broadening and dispersion compensation. The currently most effective method of nonlinear spectral broadening is self-phase modulation. The multi-pass cell (MPC) device based on self-phase modulation for broadening spectral bandwidth has been the subject of considerable interest and attention, since it was demonstrated. The MPC concept demonstrates significant practical benefits. Essentially, it requires only two curved mirrors and a Kerr medium in between, making it a cost-effective and easily implementable method. Moreover, MPCs are robust, quite insensitive to beam pointing, and can even handle small mode mismatches without transmission losses. These favorable properties have made MPCs very attractive not only for scientific applications but also for commercial and facility laser systems where reliability is of utmost importance. The striking progress of the technique in the past six years has made obtaining high average power femtosecond laser no longer a challenging task. We demonstrate the generation of a high average power femtosecond laser pulse by nonlinear compressing the picosecond pulse in the Herriott multi-pass cell device, and the distribution of eigenmode was analyzed. With this efficient and robust scheme, the spectrum was broadened from 0.20nm to 2.75nm, broaden ratio of 13.75, and the pulse duration of a picosecond amplifier is compressed from 1.25ps to 780fs, corresponding to a compression factor of 16. The average power before and after pulse compression is 100W and 71.3Wrespectively, so the overall transmission reaches 71.3%. The presented scheme offers a viable route toward low-cost and simple configuration high-power femtosecond lasers driven by Nd-doped picosecond amplifiers.