High-performance seed pulses for multi-petawatt laser

To achieve multi-petawatt pulses, the generation of high-temporal-contrast few-cycle seed pulses with the central wavelength of 910 nm is the first step. In this research, high-performance seed pulses with a spectrum ranging from 800 nm to 1050 nm and pulse energy of 86 μJ are generated based on the filtered multi-plate spectral broadening and spectral filtering from a Yb-based femtosecond laser system. With self-phase modulation (SPM) induced spectral broadening, the input with relatively narrow spectrum bandwidth is broadened widely, which enables the final output pulse be compressed from full width at half maximum (FWHM) of 190 fs to 11.2 fs and a compression ratio of about 18 after dispersion compensation. The experiments show that the temporal contrast of the final output pulse is improved by at least four orders of magnitude through spectral filtering and new spectral components generated by third-order nonlinear processes such as SPM and self-focusing. Furthermore, taking advantage of single beam and self-focusing process, the final output has high energy stability and spectrum stability. Based on the merits above, together with its simplicity and robustness, this method proposed is expected to be used for the seed pulse generation of 10s-100s petawatt (PW) level laser system in the future.