Abstract

High-energy sub-cycle optical waveforms [1] have numerous intriguing applications in attoscience and strong-field physics, e.g., in the generation of intense isolated attosecond XUV pulses [2], relativistic laser-plasma interactions and laser-driven electron acceleration [3], valence-electron wavepacket dynamics in atoms and molecules [4], and the control of sub-cycle electron transport in solids [5]. In 2013, we proposed and reported first amplification results for our multi-mJ 3-channel parametric waveform synthesizer for generating >2-octave-wide spectra with ~1.9-fs transform-limited pulse duration [6]. We performed FROG pulse-characterization of all three second-stage outputs at the waveform synthesis point [7]. Here we demonstrate for the first time the actual coherent synthesis step by active feedback stabilization of the relative timing between two channels of the multi-mJ parametric waveform synthesizer, which has much longer beam paths than previous µJ-level synthesizers (several tens of meters) [8].

© 2015 IEEE