Jielong Shi

Interactions of nonlocal dark solitons under competing cubic–quintic nonlinearities

We investigate analytically and numerically the interactions of dark solitons under competing nonlocal cubic and local quintic nonlinearities. It is shown that the self-defocusing quintic nonlinearity will strengthen the attractive interaction and decrease the relative distance between solitons, whereas the self-focusing quintic nonlinearity will enhance the repulsive interaction and increase soliton separation. We demonstrate these results by approximate variational approach and direct numerical simulation.

Anomalous bistable shift for a one-dimensional photonic crystal doped with a subwavelength layer and a nonlinear layer

It is found that a subwavelength layer of linear negative-index material (NIM) significantly modifies the characteristic of bistable shift for a one-dimensional photonic crystal containing a defect layer of NIM and a Kerr-type nonlinear-defect layer of positive-index material (PIM). Anomalous bistable shift occurs as the absolute value of magnetic permeability of the NIM layer increases. It is also found that the sequence of the thin film of NIM and the nonlinear layer has a major impact on this anomalous bistable shift. The validity of theoretical analysis is confirmed by numerical simulations for a Gaussian beam.

Nonlinear surface waves near the Dirac point in negative?zero?positive index metamaterial

Motivated by the realization of the Dirac point (DP) with a double-cone structure for the optical field in a negative–zero–positive index metamaterial (NZPIM), we study the nonlinear surface waves localized at the single interface separating a nonlinear conventional dielectric medium and a NZPIM. It is found that, near the DP, there is a forbidden band for the nonlinear surface waves and the nonlinear surface waves also have a frequency threshold. In contrast to the negative permeability of NZPIM in some frequency regions, we show that the nonlinear surface waves are always forward with positive power fluxes. The frequency property, the group velocity and the power flux of the surface waves are also discussed in detail. These results may have potential applications in guided wave optics and optical devices.

Suppression of collapse for two-dimensional Airy beam in nonlocal nonlinear media

Dynamics and collapse of two-dimensional Airy beams are investigated numerically in nonlocal nonlinear media with split step Fourier transform method. In particular, the stability and self-healing properties of the Airy beams depend crucially on the location and topological charge of the vortex when the beams carry angular momentum. The propagation of abruptly autofocusing Airy beams is also demonstrated in local and nonlocal media. In strongly self-focusing regime, with the help of nonlocality, stationary propagation of two-dimensional Airy beams can be obtained, which always collapse in local nonlinear media.

Nonlinear surface polaritons in indefinite media

We make a theoretical investigation of nonlinear surface polaritons localized at a single interface separating a nonlinear conventional dielectric medium and a linear indefinite medium. The propagation properties of such nonlinear surface polaritons are demonstrated in several distinct frequency intervals. The surface effect of optical beams suffers different dynamics from the propagation (transmission) effect in indefinite media. The existence conditions, frequency thresholds, group velocity, and the power fluxes of the nonlinear surface polaritons are also discussed in detail.

Unusual photon tunneling in the frustrated total internal reflection structure including indefinite metamaterials

The transmittance and the behavior of an evanescent field in the frustrated total internal reflection structure composed of isotropic media and anisotropic indefinite metamaterial are obtained by the transfer matrix formulation. The evanescent waves can evolve into different forms associated with the different dispersion relations of the indefinite metamaterial. In cutoff and anti-cutoff media, the evanescent waves are amplified and even total photon tunneling is obtained under some conditions. Then the evanescent wave can be transformed into a propagation wave and highly efficient tunneling is also achieved in a always-cutoff medium.

The effect of a thin film on bistable shift for a one-dimensional photonic crystal doped with a nonlinear layer

We regard the bilayer consisting of a subwavelength layer of linear negative index material (NIM) and a Kerr-type nonlinear layer of conventional positive index material as a combined defect for a one-dimensional photonic crystal and investigate the effect of the thin film on the hysteretic behavior of the Goos-Hänchen shift and the incident intensity. We find that a subwavelength layer of linear negative index material (NIM) significantly modifies the characteristic of hysteretic behavior of lateral shift for the transmitted beam. Anomalous bistable shift occurs as the absolute value of magnetic permeability of the NIM layer increases. We also find that the sequence of the thin film of NIM and the nonlinear layer has a major impact on bistable shift. These results may be useful for NIMs characterization and for designing novel photonic-crystal-based devices.

The analyses of negative refraction in finite one-dimensional photonic crystals

We theoretically investigate negative refraction in finite one-dimensional photonic crystals and discuss the dependence of negative refraction on the crystal structure, the incident angle and the background medium systematically. We find that negative refraction phenomena exist in many structures if we choose the incident angle carefully. We also find that when the crystal structure and the background medium are well matched, the power transmittance of negative refraction can be greatly improved. There shows that large negative transverse shift exists even when the power transmittance is remarkably enhanced.

Goos-Hiichen shifts for a one-dimensional photonic crystal with a nonlinear defect

The Goos-Hanchen effect for a one-dimensional photonic crystal containing a nonlinear defects is theoretically investigated. Its found that there exists a hysteresis response between the incident light intensity and the lateral shift for transmitted beams and lateral shift reaches its peak at the switch-down threshold intensity of the optical bistability. The dependence of the hysteresis on the nonlinear defect and the incident angle is discussed systematically. Its also found that for fixed structure and incident angle, the hysteresis is dependent of the frequency offset between the incident light frequency and the linear defect mode frequency. The validity of the theoretical analysis is demonstrated by numerical simulations for a Gaussian beam.