Thresholdless dressed-atom laser in a photonic band-gap material

TL;DR

This paper demonstrates a thresholdless dressed-atom laser within a photonic band-gap material, showing how spontaneous emission influences threshold behavior and highlighting nonclassical photon statistics as a signature of nonlinear lasing.

Contribution

It introduces a thresholdless lasing scheme in a dressed-atom system within a photonic band-gap, analyzing the effects of spontaneous emission on threshold behavior.

Findings

Thresholdless lasing occurs when spontaneous emission is suppressed.

Mean photon number increases nonlinearly with pumping in thresholdless operation.

Sub-Poissonian photon statistics indicate nonclassical light in the system.

Abstract

We demonstrate the capability of complete thresholdless lasing operation between dressed states of a two-level atom located inside a microscopic cavity engineered in a photonic band-gap material. We distinguish between threshold and thresholdless behaves by analyzing the Mandel's Q parameter for the cavity field. We find that the threshold behave depends on whether the spontaneous emission is or is not present on the lasing transition. In the presence of the spontaneous emission, the mean photon number of the cavity field exhibits threshold behavior indicating that the system may operate as an ordinary laser. When the spontaneous emission is eliminated on the lasing transition, no threshold is observed for all values of the pumping rate indicating the system becomes a thresholdless laser. Moreover, we find that under a thresholdless operation, the mean photon number can increase nonlinearly with the pumping rate, and this process is accompanied by a sub-Poisson statistics of the field. This suggests that the nonclassical statistics can be used to distinguish a nonlinear operation of the dressed-atom laser.