CEP-Stable, Few-Cycle, kHz OPCPAs for Attosecond Science: Energy Scaling and Coherent Sub-Cycle Pulse Synthesis

Abstract

We report on the energy scaling and coherent waveform synthesis of a carrier-envelope phase (CEP)-stable, few-cycle, kHz-repetition-rate optical parametric chirped-pulse amplifiers (OPCPAs) for high-field physics applications. First, amplification of ultrabroadband $2.1\mbox{ -}\mu \mathrm{m}$ pulses to 0.85 mJ is demonstrated using a novel high-energy, ps, cryogenic Yb:YAG pump laser. Pulse compression to 4.5 optical cycles has been achieved. Initial high-harmonic generation (HHG) experiments with Xe have shown a significant cutoff extension to $>85\,\mathrm{eV}$. Second, we have coherently synthesized the $2.1\mbox{ -}\mu \mathrm{m}$ pulse with a CEP-stable, few-cycle near-infrared OPCPA pulse seeded by the same laser oscillator and generated a $15\mbox{ -}\mu \mathrm{J}$ sub-cycle waveform. Simulations confirm that this waveform is suitable for isolated attosecond pulse generation. The pulse synthesis method can be extended to a novel energy-scalable wavelength multiplexing scheme based on multi-color OPCPAs.