Mid-infrared generation by optical frequency conversion and applications to spectroscopy and air monitoring

Continuous-wave infrared generation based on nonlinear frequency conversion is described. Broadly tunable infrared radiation was generated from 4 to 1 9 mu m by difference-frequency mixing of two optical lasers in AgGaS2 or Ga Se crystal. Related techniques encountered in power conversion efficiency, synchronously phase-matched infrared wavelength scan, extension of phase-ma tchable infrared spectral coverage, power-balanced detection, etc, are disc ussed. Applications of this nonlinear generation source to spectroscopy, as well as to environmental air monitoring are presented. (C) 1999 Elsevier S cience B.V. All rights reserved.