High-power sub-15 fs nonlinear pulse compression at 515 nm of an ultrafast Yb-doped fiber amplifier.

We present an efficient and robust scheme to produce energetic sub-15 fs pulses centered at 515 nm with a peak power exceeding 3 GW. Combining efficient second-harmonic generation of a 135 fs, 50 W Yb-doped fiber amplifier with a low-loss capillary-based visible pulse compression stage, we reach an overall efficiency higher than >20%. The system is also designed to take advantage of the repetition rate flexibility of the fiber amplifier, leading sub-15 fs pulse generation from 166 to 500 kHz with an average power exceeding the 10 watt level. The combined reduction of the laser wavelength and pulse duration is expected to highly improve the yield of high-order harmonic generation to provide high photon flux of ultrashort extreme ultraviolet radiation.

Self-compression in a multipass cell.

We demonstrate self-compression of short-wavelength infrared pulses in a multipass cell (MPC) containing a plate of silica. Nonlinear propagation in the cell in the anomalous dispersion regime results in the generation of 14 µJ 22 fs pulses at 125 kHz repetition rate and 1550 nm wavelength. Periodic focusing inside the cell allows us to circumvent catastrophic self-focusing, despite an output peak power of 440 MW well beyond the critical power in silica of 10 MW. This technique allows straightforward energy scaling of self-compression setups and control over the spatial manifestation of Kerr nonlinearity. More generally, MPCs can be used to perform, at higher energy levels, temporal manipulations of pulses that have been previously demonstrated in waveguides.