Polarization patterns and vectorial defects in type-II optical parametric oscillators

Abstract

Previous studies of lasers and nonlinear resonators have revealed that the polarisation degree of freedom allows for the formation of polarisation patterns and novel localized structures, such as vectorial defects. Type II optical parametric oscillators are characterised by the fact that the down-converted beams are emitted in orthogonal polarisations. In this paper we show the results of the study of pattern and defect formation and dynamics in a Type II degenerate optical parametric oscillator for which the pump field is not resonated in the cavity. We find that traveling waves are the predominant solutions and that the defects are vectorial dislocations which appear at the boundaries of the regions where traveling waves of different phase or wave-vector orientation are formed. A dislocation is defined by two topological charges, one associated with the phase and another with the wave-vector orientation. We also show how to stabilize a single defect in a realistic experimental situation. The effects of phase mismatch of nonlinear interaction are finally considered.

Dynamics of defects in the vector complex Ginzburg–Landau equation

“…However in the cases in which the polarization of the light is not fixed, the vector nature of the electromagnetic field leads to striking topological phenomena [3]. Recently reported examples of localized structures for which the polarization plays a fundamental role include points of zero amplitude in both components of the field in a periodic elliptically polarized background, found in type II OPO [4] and dots of low amplitude in a circularly polarized component of the field in an almost circularly polarized background found in self-defocusing vectorial Kerr resonators [5].…”

Self-organization, pattern formation, cavity solitons, and rogue waves in singly resonant optical parametric oscillators

“…Self-organization and pattern formation in OPOs has been known for a number of years in degenerate [8] or doubly or triply resonant non-degenerate configurations [19][20][21]. The case of a widely non-degenerate SROPO has, however, been overlooked because of experimental limitations, now overcome, and the fact that offresonance operation is inhibited because of its intrinsic tuneability.…”

“…We assume that the parametric down conversion crystal is contained in an optical cavity of length L where the signal field is the only one to be resonated (see Figure 1). The steps involved in taking the mean-field approximation are the same as those reported in [21] although in the SROPO case there is only one resonated field. The final equation for the normalized signal field reads as:…”

Transverse dynamics in cavity nonlinear optics (2000–2003)

“…Close to threshold a linear stability predicts standing waves with the same wavelength for the two polarization components [82]. In this device, waves are the predominant solutions and the defects are vectorial dislocations that appear at the boundaries of domains where travelling waves of different phases or wavevector orientations are formed [83]. The walk-off effect on pattern selection in the DOPO was also studied [84].…”