Parametric amplification of few-cycle carrier-envelope phase-stable pulses at 21 μm

We demonstrate an optical parametric chirped-pulse amplifier producing infrared $20\mathrm{fs}$ (3-optical-cycle) pulses with a stable carrier-envelope phase. The amplifier is seeded with self-phase-stabilized pulses obtained by optical rectification of the output of an ultrabroadband Ti:sapphire oscillator. Energies of $\sim 80\mu \mathrm{J}$ with a well-suppressed background of parametric superfluorescence and up to $400\mu \mathrm{J}$ with a superfluorescence background are obtained from a two-stage parametric amplifier based on periodically poled $\mathrm{Li}\mathrm{Nb}{\mathrm{O}}_3$ and $\mathrm{Li}\mathrm{Ta}{\mathrm{O}}_3$ crystals. The parametric amplifier is pumped by an optically synchronized $1\mathrm{kHz}$, $30\mathrm{ps}$, $1053\mathrm{nm}$ Nd:YLF amplifier seeded by the same Ti:sapphire oscillator.