Temporal contrast enhancement by self-phase modulation in a multi-pass cell with excellent beam quality and pointing stability

We demonstrate the temporal contrast enhancement via self-phase modulation followed by spectral filtering in a gas-filled multi-pass cell (MPC). The performance of the temporal cleaning device has been thoroughly investigated, covering spectral broadening, efficiency, temporal contrast enhancement, power stability, beam quality and beam pointing stability. The total efficiency of our device exceeding 30%, with a pulse energy of 555 μJ. The temporal contrast of the filtered pulse enhances more than two orders of magnitude, which surpassing 109. The filtered laser beam exhibits excellent beam quality and pointing stability with M2 values of 1.12 ×1.14 and angular pointing stability of 1.90 μrad×2.05 μrad. This method, followed by a second-stage spectral broadening unit, can be easily applied to ultra-broadband high peak power laser systems, with such high beam quality, excellent power stability and amazing pointing stability.