Abstract
The repetition rate of few-cycle intense pulses should be increased for improving the signal-to-noise ratio of nonlinear optical measurement technologies such as attosecond spectroscopies. A promising way of doing so is to use Yb amplifiers, which can operate at MHz repetition rates and have recently become commercially available. The current ways of generating intense MHz few-cycle pulses include optical parametric chirped amplification (OPCPA) using Yb amplifiers as a pump light source and pulse compression of the Yb-laser pulses itself. Thermal damage to nonlinear crystals remains a bottleneck of OPCPA to achieving high average output power despite intensive investigations [1,2]. In contrast, pulse compression is currently a leading candidate for high-average-power operation [3]. It has been used for MHz sub-two-cycle pulse generation with hollow-core fiber (HCF) compression [4]. Another compression scheme is a solid-based method, e.g. the multi-plate continuum (MPC) method [5]. Its advantages include higher throughput, compactness, and easier alignment. However, the applicability of the MPC method to 100-W-class laser pulses has remained unclear. Here, we demonstrate MHz operation of 1.7-cycle intense pulses with a pulse energy of 35 µJ by compressing 80-W Yb:KGW laser pulses via the MPC method.