We demonstrate the sub-100 fs pulse generation from a dispersion-managed mode-locked Er:ZBLAN fiber laser at 2.8 μm. Both numerical simulation and experiment demonstrate that stretched-pulse and dissipative soliton mode lockings coexist in the near-zero-dispersion region of a fluoride fiber laser. With fine dispersion management, the shortest pulse of 95 fs was obtained from the stretched-pulse mode-locked Er:ZBLAN fiber laser, with an average power of 280 mW and repetition rate of 52 MHz. To the best of our knowledge, this is the shortest pulse to date directly generated from a mid-infrared mode-locked fluoride fiber laser.

We report dispersion management based on a mismatched-grating compressor for a 100 PW level laser, which utilizes optical parametric chirped pulse amplification and also features large chirped pulse duration and an ultra-broadband spectrum. The numerical calculation indicates that amplified pulses with 4 ns chirped pulse duration and 210 nm spectral bandwidth can be directly compressed to sub-13 fs, which is close to the Fourier-transform limit (FTL). More importantly, the tolerances of the mismatched-grating compressor to the misalignment of the stretcher, the error of the desired grating groove density and the variation of material dispersion are comprehensively analyzed, which is crucially important for its practical application. The results demonstrate that good tolerances and near-FTL compressed pulses can be achieved simultaneously, just by keeping a balance between the residual second-, third- and fourth-order dispersions in the laser system. This work can offer a meaningful guideline for the design and construction of 100 PW level lasers.