High temporal contrast ultrashort pulses generated by nonlinear ellipse rotation in multipass cells

The simultaneous nonlinear spectral broadening and temporal cleaning of ultrashort pulses by the combination of the multipass cell (MPC) technique and nonlinear ellipse rotation are proposed and investigated with numerical simulations. The performance of the gas-filled MPC is studied at 800 and 1030 nm central wavelengths with mJ energy level. The results indicate that at least 103 contrast enhancement is feasible with 50% internal efficiency while the beam quality is preserved during propagation. At the same time, nonlinear spectral broadening allows for a more than five-fold temporal compression. The technique is tested at 20 mJ energy and it is presumably suitable for the generation of high contrast, high energy few-cycle pulses, too.