Coherent control of the refractive index using optical bistability

TL;DR

This paper demonstrates how optical bistability in a three-level atomic medium can be used to coherently control the refractive index and absorption, leading to dynamic, time-dependent changes in optical properties.

Contribution

It introduces a novel method to manipulate the refractive index via optical bistability, including the discovery of nonlinear dynamical instability and self-pulsing effects.

Findings

Refractive index can be switched between normal and anomalous dispersion.

Bistable control field induces periodic self-pulsing and susceptibility variation.

Unstable lower bistable branch leads to nonlinear dynamical behavior.

Abstract

Refractive index and absorption experienced by a probe field propagating through a three-level atomic medium can be effectively manipulated by the bistable behavior of a control field. The probe field couples the lower transition of the atom in ladder configuration and experiences normal or anomalous dispersion depending on the control field being in the upper or lower bistable state, respectively. We also obtain nonlinear dynamical instability in the form of periodic self-pulsing as the lower bistable branch becomes unstable, quite unlike earlier demonstrations of unstable regime in the upper branch. Consequently, the susceptibility experienced by the probe field varies periodically in time dictated by the control field self-pulsing.