Observation of optical solitons in PT-symmetric lattices

Abstract

Controlling light transport in nonlinear active environments is a topic of considerable interest in the field of optics. In such complex arrangements, of particular importance is to devise strategies to subdue chaotic behaviour even in the presence of gain/loss and nonlinearity, which often assume adversarial roles. Quite recently, notions of parity-time (PT) symmetry have been suggested in photonic settings as a means to enforce stable energy flow in platforms that simultaneously employ both amplification and attenuation. Here we report the experimental observation of optical solitons in PT-symmetric lattices. Unlike other non-conservative nonlinear arrangements where self-trapped states appear as fixed points in the parameter space of the governing equations, discrete PT solitons form a continuous parametric family of solutions. The possibility of synthesizing PT-symmetric saturable absorbers, where a nonlinear wave finds a lossless path through an otherwise absorptive system is also demonstrated.

Resonant interaction of ϕ4 kink with PT-symmetric perturbation with spatially periodic gain/loss coefficient

“…Presumably, such features are of broader physical interest and relevance than the specifics of our φ 4 example. In light of the recent realization of optical solitons in PT -symmetric lattices [45], it would be interesting to extend relevant notions to nonlinear Schrödinger classes of models, especially since recent work has developed non-conservative variational approximations in the latter context [46]. These directions are currently under investigation and will be reported in future publications.…”

A PT -Symmetric Dual-Core System with the Sine-Gordon Nonlinearity and Derivative Coupling

“…It is easy to see that the Hamiltonian density defined by Equation (3) has a minimum only at the FP given by Equation (28), while the FPs given by Equations (29)-(31) correspond to a maximum or saddle points, respectively; hence, stable FPs may be produced solely by Equation (28) (for this reason, the detailed stability analysis, which produces Equations (14)- (17), was presented above only for this type of the FP). The KK and KA complexes should connect the FPs with different values of n; hence, these complexes represent heteroclinic trajectories of the dynamical system based on Equations (25) and (26).…”

Self-collimation in PT -symmetric crystals

“…These are complex crystals, where real (refractive index) and imaginary (gainloss) modulations of the refractive index are dephased π/2, holding potentially technologically important properties such as asymmetrical coupling, asymmetrical reflections, abrupt phase transitions, and loss-induced transparency. In optics, such complex crystals have been already explored in various contexts: field localization [25], unidirectional transmission [26], defect states [27], optical solitons [28], asymmetric chirality [29], and cloaking [30].…”