Generation of high-repetition-rate, high-power, few-cycle, 2-µm laser pulses with a single-stage all-fiber nonlinear compressor

We demonstrate a high-repetition-rate, high-power, few-cycle 2-µm laser employing a single-stage, all-fiber nonlinear pulse compressor. The compressor consists of three cascaded dispersion-compensating fibers that are spliced, with group velocity dispersions of -0.095 ps²/m, 0.137 ps²/m, and -0.076 ps²/m, respectively. The splicing losses caused by the different mode-field diameters were carefully minimized to 0.8 dB and 0.23 dB. A home-built 51.6-MHz, 8.26-W, 578-fs Tm-doped laser was used as the driving laser. This nonlinear fiber compressor realized a compression ratio of 17, reducing the pulse duration to 34 fs, based on the Gaussian assumption. The interaction between the accumulated nonlinear phase and dispersion was analyzed to optimize the characteristics of the compressed pulse. Consequently, laser pulses with 4.4-W average power and a 34-fs duration were generated.