Broadband nanosecond optical parametric chirped-pulse amplification with a double-sliced pump pulse

We developed a two-stage optical parametric chirped-pulse amplification (OPCPA) amplifier with a double-sliced pump pulse. To utilize a single-longitudinal laser pulse with an 8-ns duration and a 532-nm central wavelength as a high-energy pump source efficiently, two 2-ns quasi-rectangular pump pulses were generated by double-slicing the green pulse with two Pockels cells. The energy and spectral width of the amplified laser pulse with an 820-nm central wavelength were maximized by optimizing the phase matching conditions in the OPCPA amplifier via a 3-D simulation. The amplified laser pulse had a broad bandwidth of 120 nm (FWHM) and a high energy of 75 mJ. And the amplified pulse had an energy stability of 2.14% (RMS) on account of the temporal jittering between the single-mode green pulse and the Pockels cells while the single-mode green pump laser had an energy stability of 1.1% (RMS).