Abstract

The fundamental process of the optical parametric oscillator is a parametric coupling of three monochromatic waves. Three wave interaction of focused Gaussian fields was first considered by Boyd and Kleinmann in the late sixties. In their work the interaction of the three beams was computed as an overlap integral throughout the crystal resulting in the so-called Boyd-Kleinman reduction factor. Their analysis also takes into account walk-off associated with an extraordinarily polarised beam propagating in a birefringent crystal. Their description was, however, limited to either ordinary polarised pump and extraordinary polarised signal and idler (oee) or extraordinary polarised pump and ordinary polarised signal and idler fields (eoo), usually denoted Type I phase matched interaction. In the following a generalised theory including arbitrary confocal parameters for the three beams and independent walk-off of any two beam pairs as it occurs in Type II phase matching will be derived.

© 1998 IEEE