Optical parametric generation of a mid-infrared continuum in orientation-patterned GaAs

We have generated an ultrabroad mid-infrared continuum by using single-pass optical parametric generation (OPG) in orientation-patterned GaAs (OP-GaAs). The spectrum spans more than an octave, from 4.5 to 10.7 eta m, measured 20 dB down from the peak. The 17.5 ram long, 0.5 mm thick, all-epitaxially-grown OPGaAs sample with a 166.6-mu m quasi-phase-matching period was pumped with 3.1-3.3 mu m wavelength, 1 ps pulses up to 2 mu J in energy. The OPG threshold was observed at 55 nJ pump energy with the pump polarized along the [111] crystal direction. The slope efficiency near threshold was 51%, and the external conversion efficiency was as high as 15%. (c) 2006 Optical Society of America