Retracing behavior and broadband generation based on quasi-phase-matched optical parametric processes

Broadband operation based on retracing behavior (RB) of the phase-matching curves in various quasi-phase-matched materials with collinear, non-collinear, and quasi-collinear phase-matching schemes is theoretically studied. Broadband operation is feasible only at the degenerate point in a collinear configuration with a specific pump wavelength, lambda(BC). Such a constraint sets a significant limitation on application of that scheme. With a noncollinear or a quasi-collinear phase-matching configuration the conditions and the resultant output signal ranges of broadband operation are much more flexible, particularly those that are useful for fiber communications and optical imaging of biological tissues. In a signal-resonated (idler-resonated) optical parametric oscillator (OPO) with a noncollinear or a quasi-collinear configuration, RB and hence broadband operation can be observed only for pump wavelengths shorter (longer) than lambda(BC). Also, broadband operation for an idler-resonated OPO with a pump wavelength longer than lambda(BC) can be obtained only at the degenerate point. Nevertheless, broadband phenomena for a signal-resonated OPO with a pump wavelength shorter than lambda(BC) can be observed either at or away from the degenerate points. (C) 2002 Optical Society of America.