We demonstrate that in-bulk vortex localized modes, and their surface half-vortex (“horseshoe”) counterparts (which were not reported before in truncated settings) self-trap in two-dimensional (2D) nonlinear optical systems with PT-symmetric photonic lattices (PLs). The respective stability regions are identified in the underlying parameter space. The in-bulk states are related to truncated nonlinear Bloch waves in gaps of the PL-induced spectrum. The basic vortex and horseshoe modes are built, severally, of four and three beams with appropriate phase shifts between them. Their stable complex counterparts, built of up to 12 beams, are reported too.

http://arxiv.org/abs/1403.4745
Optics (physics.optics); Pattern Formation and Solitons (nlin.PS)

We introduce a novel concept of the {\em pseudo} parity-time (\(\mathcal{PT}\)) symmetry in periodically modulated optical systems with balanced gain and loss. We demonstrate that whether the original system is \(\mathcal{PT}\)-symmetric or not, we can manipulate the property of the \(\mathcal{PT}\) symmetry by applying a periodic modulation in such a way that the effective system derived by the high-frequency Floquet method is \(\mathcal{PT}\) symmetric. If the original system is non-\(\mathcal{PT}\) symmetric, the \(\mathcal{PT}\) symmetry in the effective system will lead to quasi-stationary propagation that can be associated with the \emph{pseudo \(\mathcal{PT}\) symmetry}. Our results provide a promising approach for manipulating the \(\mathcal{PT}\) symmetry of realistic systems.

http://arxiv.org/abs/1302.1091
Optics (physics.optics); Quantum Physics (quant-ph)