Laser refrigeration using exciplex resonances in gas filled hollow-core fibres

TL;DR

This paper explores a theoretical approach to macroscopic laser refrigeration using exciplex resonances in gas-filled hollow-core fibers, modeling the dynamics and deriving scaling laws for cooling performance.

Contribution

It introduces a new theoretical framework for laser cooling via exciplex-mediated up-conversion in hollow-core fibers, including detailed modeling and scaling laws.

Findings

Efficient kinetic energy extraction cycles via exciplex states.

Derived scaling laws for cooling power and rates.

Identified parameters affecting cooling efficiency.

Abstract

We theoretically study prospects and limitations of a new route towards macroscopic scale laser refrigeration based on exciplex-mediated frequency up-conversion in gas filled hollow-core fibres. Using proven quantum optical rate equations we model the dynamics of a dopant-buffer gas mixture filling an optically pumped waveguide. In the particular example of alkali-noble gas mixtures, recent high pressure gas cell setup experiments have shown that efficient kinetic energy extraction cycles appear via the creation of transient exciplex excited electronic bound states. The cooling cycle consists of absorption of lower energy laser photons during collisions followed by blue-shifted spontaneous emission on the atomic line of the alkali atoms. For any arbitrary dopant-buffer gas mixture, we derive scaling laws for cooling power, cooling rates and temperature drops with varying input laser power, dopant and buffer gas concentration, fibre geometry and particularities of the exciplex ground and excited state potential landscapes.