Lasing in the superradiant crossover regime

TL;DR

This paper explores superradiant and conventional lasing regimes using ultra-cold alkaline earth atoms in optical cavities, demonstrating narrow linewidths and coherence properties relevant for advanced laser development.

Contribution

It analyzes two experimentally feasible superradiant lasing regimes, confirming narrow linewidths and coherence effects in strontium atoms, advancing understanding of superradiant laser physics.

Findings

Narrow linewidth confirmed for superradiant lasing in strontium-87

Linewidth narrows further under strong driving of strontium-88 transition

Different lasing regimes distinguished by atomic and cavity coherence

Abstract

A new class of laser, which harnesses coherence in both light and atoms, is possible with the use of ultra-cold alkaline earth atoms trapped in an optical lattice inside an optical cavity. Different lasing regimes, including superradiance, superradiant and conventional lasing, are distinguished by the relative coherence stored in the atoms and in the cavity mode. We analyze the physics in two different experimentally achievable regions of the superradiant lasing regime. Our calculations confirm the narrow linewidth of superradiant lasing for the doubly forbidden clock transition ${}^3 P_0 \to {}^1 S_0$ of strontium-87 atoms. Under strong driving of the dipole-forbidden transition ${}^3 P_1 \to {}^1 S_0$ of strontium-88 atoms the superradiant linewidth narrows further due to the coherent excitation of the cavity field.