Generation of carrier-envelope-phase-stable 2-cycle 740-μJ pulses at 21-μm carrier wavelength

We produce carrier-envelope-phase-stable 15.7-fs (2-cycle) 740-microJ pulses at the 2.1-microm carrier wavelength, from a three-stage optical parametric chirped-pulse amplifier system, pumped by an optically synchronized 49-ps 11-mJ Nd:YLF laser. A novel seed pulse spectral shaping method is used to ascertain the true amplified seed energy and the parametric superfluorescence levels.