Emission spectra and intrinsic optical bistability in a two-level medium

TL;DR

This paper theoretically investigates the emission spectra and intrinsic optical bistability in a dense two-level medium, analyzing spectral patterns and their control via incident light intensity, with implications for understanding nonlinear light-matter interactions.

Contribution

It derives analytical response spectra for the entire hysteresis loop of atomic excitation considering local field effects and provides a formula to distinguish mechanisms of intrinsic bistability.

Findings

Spectral patterns switch with incident field strength.

Analytical spectra are obtained for the hysteresis loop.

The emission spectra formula helps identify bistability mechanisms.

Abstract

Scattering of resonant radiation in a dense two-level medium is studied theoretically with account for local field effects and renormalization of the resonance frequency. Intrinsic optical bistability is viewed as switching between different spectral patterns of fluorescent light controlled by the incident field strength. Response spectra are calculated analytically for the entire hysteresis loop of atomic excitation. The equations to describe the non-linear interaction of an atomic ensemble with light are derived from the Bogolubov-Born-Green-Kirkwood-Yvon hierarchy for reduced single particle density matrices of atoms and quantized field modes and their correlation operators. The spectral power of scattered light with separated coherent and incoherent constituents is obtained straightforwardly within the hierarchy. The formula obtained for emission spectra can be used to distinguish between possible mechanisms suggested to produce intrinsic bistability.