Abstract

Out of various techniques for generation of tunable infrared radiation, nonlinear difference frequency mixing (DFM) is the simplest one. Though optical parametric oscillation (OPO) and amplification (OPA) are very powerful techniques in wavelength extension in the infrared region, the higher gain of the latter process demands a laser pump source that has an exceptionally good beam quality (preferably with a single transverse and a single longitudinal mode) and very good crystal quality of large size. For DFM these requirements are not so stringent. Moreover special measures are needed to be taken to suppress the linewidth of OPO and OPA signals while for DFM the linewidth of the generated signal is determined by that of the input radiations and the phase-matching acceptance of the crystal.

© 1995 IEEE