Carrier-envelope phase-stable few-cycle pulses from two stage hybrid compression of a Yb:KGW amplifier

Abstract Next-generation attosecond spectroscopies require high-repetition-rate driving lasers with few-cycle pulse duration, stable carrier-envelope phase (CEP), and ease of operation. Industrial-grade Yb-doped solid-state regenerative amplifiers perform very well at high repetition rates, but their relatively long pulse durations necessitate post-compression techniques with large compression factor to reach the few-cycle limit. Here, we demonstrate the two-stage hybrid nonlinear compression of 280 fs pulses from a Yb:KGW regenerative amplifier to 5.6 fs, 142 μJ, with an overall transmission efficiency of >70%. In the first stage, a gas filled multi-pass cell is used to compress the pulses down to 38 fs, while a second stage gas filled hollow-core fiber further compresses the pulses to below two optical cycles. We also demonstrate the stabilization of the CEP in the compressed pulse, with a measured root-mean-squared error of 423 mrad on a shot-to-shot basis.