A generic photonic coupler with active and lossy parts, gain saturation, and asymmetric
characteristics is examined. Saturable activity is shown to be able to enhance the overall …

Abstract Parity-time (PT)-symmetry in optics is a condition whereby the real and imaginary
parts of the refractive index across a photonic structure are deliberately balanced. This …

Parity-time (PT) symmetric lasers exploit the modulation of optical gain and loss and have
led to important fundamental demonstrations in non-Hermitian physics. The current …

We consider $\mathcal {PT} $-symmetric ring-like arrays of optical waveguides with purely
nonlinear gain and loss. Regardless of the value of the gain-loss coefficient, these systems …

Vacuum consists of a bath of balanced and symmetric positive-and negative-frequency
fluctuations. Media in relative motion or accelerated observers can break this symmetry and …

This article investigates the first integrals and closed-form solutions of some nonlinear first-
order dynamical systems from diverse areas of applied mathematics. We use the notion of …

We investigate the dynamics of a coupled waveguide system with competing linear and
nonlinear loss-gain profiles which can facilitate power saturation. We show the usefulness of …

Nonlinear non-Hermitian systems with saturable nonlinearities give rise to versatile
phenomena that have no counterparts in linear systems. Here, we theoretically and …

We explore the parity-time-(⁠ PT⁠)-symmetric optical couplers with the cubic both self-and
cross-interactions corresponding to self-and cross-phase modulations. When the coefficient …

This article presents a finite dimensional unbreakable PT-symmetric waveguide system with
linear and nonlinear coupling. In traditional PT-symmetric systems, a balance (or a …