In this study we investigate the formation and propagation of pulse pairs in a quadratically nonlinear crystal containing two waveguides. The analysis focuses on how changes in parameters such as the relative positions of the waveguides, waveguide widths, and angle of entry influence the system. We observe that the pulse propagation mode varies with changes in the characteristics of the waveguides and the angle at which the pulses enter the medium.
We study a possibility spatiotemporal optical vortices propagating in a structure consisting of two connected waveguides with quadratic nonlinearity. The system under study is a planar nonlinear crystal whose refractive index in cross-section has two maxima corresponding to two waveguides. In this case, the electromagnetic field can penetrate between the waveguides, and due to that a communication between waveguides is realized. We focus on the study of the propagation dynamics of spatiotemporal optical vortices in such a system varying the distance between waveguides, the initial time shift between beams, and the initial phase shift between them.
Recently a possibility of the formation of “dancing” light bullets was analytically shown in graded-index waveguides with both Kerr and quadratic nonlinearities. At that, a two-color “dancing” light bullet in a quadratic nonlinear waveguide may form at both anomalous and normal group velocity dispersion at the fundamental frequency. Here and in what follows we refer as “dancing” light (optical) bullets spatiotemporal solitons whose trajectories can be spatial Lissajous figures with anisotropic spatial distribution of the refractive index in the cross section of the waveguide. Stability of a two-color “dancing” light bullet was theoretically demonstrated without additional conditions for its temporal duration, aperture, and power. These results were established with the help of the averaged Lagrangian method in the framework of the quasi-optical approach under the conditions of phase and group matching. The mentioned conditions are known to be hardly achievable in experiment. In the present work we study two- color “dancing” light bullet generation by means of numerical simulation including the cases when only one of the conditions of synchronism is fulfilled. We demonstrate that a pulse at the doubled frequency is generated in the waveguide at second harmonic generation (SHG), followed by the formation of the bound state of both harmonics representing a two-color “dancing” light bullet
In general, optical spatiotemporal solitons with phase singularities, known as optical vortex bullets, are unstable. In particular, it is very difficult to preserve a vortex structure of a propagating localized wave. In this paper we propose to introduce absorption to the model used for the process description. By means of numerical simulation we study the formation and propagation of an optical vortex bullet at different regimes. Our goal is to find the conditions of bullet stabilization.
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