Search

We have recently demonstrated that higher-order exceptional points can be engineered in PT symmetric networks by means of recursive bosonic algebra. In these systems, as well as in simple PT dimers with second-order exceptional points, transitions between the broken and unbroken phases take place along specific trajectories in the parameter space. Here we show that the behaviour along some of these trajectories can be reversed through the inclusion of strongly coupled passive dimers that act as two-mode adiabatic bridges connecting different parts of the network. We illustrate our results by first discussing the case of a simple PT dimer before we demonstrate how the same technique can be employed in configurations that exhibit third- and fourth-order exceptional points.

We have recently investigated lasing behavior in two-cavity photonic molecules and demonstrated that the phenomenon of laser self-termination is a purely linear effect associated with exceptional points or avoided crossings. Here we show that under the appropriate conditions, this effect can also exist in more complex discrete structures made of three-cavity photonic molecule lasers. Furthermore, our simulations show that the behavior predicted here is persistent when gain saturation nonlinearity is taken into account.

The concept of non-Hermitian parametric amplification was recently proposed as a means to achieve an efficient energy conversion throughout the process of nonlinear three wave mixing in the absence of phase matching. Here we investigate this effect in a waveguide coupler arrangement whose characteristics are tailored to introduce passive PT symmetry only for the idler component. By means of analytical solutions and numerical analysis, we demonstrate the utility of these novel schemes and obtain the optimal design conditions for these devices.

Defining a quantum mechanical wavefunction for photons is one of the remaining open problems in quantum physics. Thus quantum states of light are usually treated within the realm of second quantization. Consequently, spontaneous emission (SE) in arbitrary photonic media is often described by Fock space Hamiltonians. Here, we present a real space formulation of the SE process that can capture the physics of the problem accurately under different coupling conditions. Starting from first principles, we map the unitary evolution of a dressed two-level quantum emitter onto the problem of electromagnetic radiation from a self-interacting complex harmonic oscillator. Our formalism naturally leads to an efficient computational scheme of SE dynamics using finite difference time domain method without the need for calculating the photonic eigenmodes of the surrounding environment. In contrast to earlier investigations, our computational framework provides a unified numerical treatment for both weak and strong coupling regimes alike. We illustrate the versatility of our scheme by considering several different examples.

We study Anderson localization dynamics in periodically modulated optical Bloch arrays. Using an effective model, we show that, in such arrangements, even a weak disorder may play an important role and can lead to enhanced Anderson localization effects.

In this paper, we present the observation of light-induced self- synchronizing flow patterns in a light-fluid system. A light beam induces local flow patterns in a fluid, which oscillate periodically or chaotically in time. The oscillations within different regions of the fluid interact with each other through heat- and surface-tension-induced fluid waves, and they become synchronized. We demonstrate optical control over the state of synchronization and over the temporal correlation between different parts of the flow field. Finally, we provide a model to elucidate these results and we suggest further ideas on light controlling flow and vice versa.

We present closed form solutions to a certain class of one- and two-dimensional nonlinear Schr¨ odinger equations involving potentials with broken and unbroken PT symmetry. In the one-dimensional case, these solutions are given in terms of Jacobi elliptic functions, hyperbolic and trigonometric functions. Some of these solutions are possible even when the corresponding PT -symmetric potentials have a zero threshold. In two-dimensions, hyperbolic secant type solutions are obtained for a nonlinear Schr¨ odinger equation with a nonseparable complex potential.