Optical parametric oscillator generates continuously tunable 6–14-µm output

Researchers led by Suresh Chandra and Toomas H. Allik of Science Applications International Corp. (McLean, VA) have generated continuously tunable output in the 6–14-µm atmospheric transmission window with a silver gallium selenide (AgGaSe₂) optical parametric oscillator (OPO). When pumped by the 1.57-µm signal of a Nd:YAG-pumped noncritically phased-matched potassium titanyl phosphate (KTP) OPO, the angle-tuned AgGaSe₂ OPO yielded the tunable output at energies up to 1.2 mJ/pulse with bandwidths of about 5 cm^-1 (FWHM) using a 6.5 × 6.5 × 35.3-mm-long type I AgGaSe₂ crystal.

The team demonstrated the usefulness of the idler output from the OPO as an optical source for a double-beam infrared spectrophotometer by obtaining the 6–12-µm spectrum of polystyrene. Government funding agencies are "very much interested in commercializing this technology," said Chandra, noting the potential of such OPOs to provide 8–12-µm output for lidar applications that are hampered by the gaps and depth resolution of CO₂ laser pulses.