Widely Tunable, Narrow-Linewidth, High-Peak-Power, Picosecond Midinfrared Optical Parametric Amplifier

We report a widely tunable, narrow-linewidth, midinfrared cascaded optical parametric generator-optical parametric amplifier (OPG-OPA) based on orientation-patterned GaAs pumped by a 46-ps, 1-MHz, 1952-nm diode-seeded thulium(Tm) doped fiber master oscillator power amplifier (MOPA). The Tm-doped-fiber MOPA beam was split by a polarizing beam splitter into two arms to pump the OPG and OPA stages, respectively. The generated signal from the OPG was spectrally filtered by a diffraction grating combined with an adjustable aperture to act as the tunable seed light for the OPA. Widely tunable output in the range of 2552-2960 nm (signal) and 5733-8305 nm (idler) was obtained from the OPA with narrow linewidths of 1.4 cm
^-1
(signal, 2942 nm) and 9 cm
^-1
(idler, 5800 nm), respectively. The maximum pulse energy of 0.40 μJ (signal, 2942 nm) and 0.16 μJ (idler, 5800 nm) was obtained at an overall conversion efficiency of 22.4% for the OPA stage. The pulse duration of the generated signal was 36 ps and assuming the generated idler had the same pulse duration the corresponding maximum peak powers were calculated to be 11.1 kW (signal) and 4.5 kW (idler), respectively.