Generation of 49 fs, 41 MW peak power pulses from fiber laser using nonlinear compression in rod type fiber

Abstract

The generation of high-average-power, high peak-power, ultra-short pulses has numerous applications in medicine, micromachining and fundamental science. Towards such a very challenging achievement, CPA Yb-doped fiber chains have been recently proved to be a very attractive alternative to the well established Ti:Sapphire based technology. Nevertheless, high peak-power highly energetic ultra-short pulses are difficult to access in these systems due to either non-linear limitations or gain narrowing. Recently, it has been shown that an Yb-doped fiber amplifier (YDFA) system based on the direct amplification of femtosecond pulse could result in the generation of sub 70 fs pulses of 16 MW peak power [1]. An alternative approach could be the nonlinear post-compression. A fiber CPA based system could be used to provide high energy pulses in the sub-picosecond regime followed by a stage of nonlinear spectral broadening, due to self phase modulation (SPM), and a compressor. A significant reduction of the pulse duration, by a factor of 5–10, compared to the initial pulse width can be obtained [2]. This technique resulted, up to now, 1 µJ pulses of 20 MW peak power [3]. In this contribution we report the use, for the first time, of a rod-type photonic crystal fiber as the passive nonlinear element to provide the SPM induced spectral broadening at even higher energy level. Moreover, the uncompensated non-linear residual spectral phase, a crucial point for the compressed pulse quality, has been carefully studied.