The PT Symmeter » University of Hyderabad

Cavity controlled spectral singularity

dwh — Sat, 07 Jun 2014 08:10:40 +0000

K. Nireekshan Reddy, S. Dutta Gupta

We study theoretically a PT-symmetric saturable balanced gain-loss system in a ring cavity configuration. The saturable gain and loss are modeled by two-level medium with or without population inversion. We show that the specifics of the spectral singularity can be fully controlled by the cavity and the atomic detuning parameters. The theory is based on the mean-field approximation as in standard theory of optical bistability. Further, in the linear regime we demonstrate the regularization of the singularity in detuned systems, while larger input power levels are shown to be adequate to limit the infinite growth in absence of detuning

http://arxiv.org/abs/1405.6812
Optics (physics.optics)

A study of PT-symmetric Non-linear Schroedinger Equation

dwh — Thu, 27 Feb 2014 11:07:07 +0000

K. Nireekshan Reddy, Subhrajit Modak, Kumar Abhinav, Prasanta K. Panigrahi

Systems governed by the Non-linear Schroedinger Equation (NLSE) with various external PT-symmetric potentials are considered. Exact solutions have been obtained for the same through the method of ansatz, some of them being solitonic in nature. It is found that only the unbroken PT-symmetric phase is realized in these systems, characterized by real energies.

http://arxiv.org/abs/1402.5762
Quantum Physics (quant-ph)

Regularization of the spectral singularity in PT-symmetric systems by all order nonlinearities: Nonreciprocity and optical isolation

dwh — Thu, 31 Oct 2013 09:08:50 +0000

Xuele Liu, Subhasish Dutta Gupta, G.S. Agarwal

Spectral singularities are ubiquitous with PT-symmetry leading to infinite transmission and reflection coefficients. Such infinities imply the divergence of the fields in the medium thereby breaking the very assumption of the linearity of the medium used to obtain such singularities. We identify saturable nonlinearity retaining contributions from all orders of the field to limit the infinite growth and regularize the spectral singularity. We present explicit numerical results to demonstrate regularization. The all order nonlinear PT-symmetric device is shown to exhibit very effective isolation or optical diode action, since transmission through such a system is nonreciprocal. In contrast, a linear system or a system with Kerr nonlinearity is known to have only reciprocal transmission. Further we demonstrate optical bistability for such a system with high contrast.

http://arxiv.org/abs/1310.8282

Optics (physics.optics)