Solid hydrogen Raman shifter for the mid-infrared range (4.4-8 mu m)

We developed a pulsed, continuously tunable laboratory laser source for the mid-infrared spectral range of 4.4-8 mum, which is characterized by the spectral linewidth of 0.4 cm(-1). The device is based on the stimulated backward Raman scattering in solid para-hydrogen at T = 4 K. It is pumped by a focused beam obtained from a commercial near-infrared optical parametric oscillator with output energy of similar to20 mJ (7-ns pulse). Output energies range from 1.7 mJ at 4.4 mum to 120 muJ at 8 mum, which correspond to quantum efficiencies of 0.53 and 0.08, respectively. Spectra of NO, H2O, and CH4 molecules in the mid-infrared were recorded. The operation of the Raman cell pumped with 532-nm radiation was also studied. (C) 2004 Optical Society of America.