Thermalization of a two-dimensional photon gas in a polymeric host matrix

TL;DR

This paper demonstrates the thermalization of a two-dimensional photon gas within a polymer host matrix, showing potential for solid-state photon Bose-Einstein condensation and energy applications.

Contribution

It introduces a dye-doped polymer host for photon thermalization, extending previous liquid dye systems to solid-state microcavities.

Findings

Thermalized photon gas observed in polymer-based microresonator.

Dye molecules in polymers maintain fluorescence properties suitable for thermalization.

Solid-state dye systems could enable photon Bose-Einstein condensation.

Abstract

We investigate thermodynamic properties of a two-dimensional photon gas confined by a dye-filled optical microcavity. A thermally equilibrated state of the photon gas is achieved by radiative coupling to a heat bath that is realized with dye molecules embedded in a polymer at room temperature. The chemical potential of the gas is freely adjustable. The optical microcavity consisting of two curved mirrors induces both a non-vanishing effective photon mass and a harmonic trapping potential for the photons. While previous experiments of our group have used liquid dye solutions, the measurements described here are based on dye molecules incorporated into a polymer host matrix. We describe studies of fluorescence properties of dye-doped polymers, and discuss the applicability of Kennard-Stepanov theory in this system. We observe a thermalized two-dimensional photon gas in the solid state based microresonator system. In the future, dye-based solid state systems hold promise for the realization of single-mode light sources in thermal equilibrium based on Bose-Einstein condensation of photons, as well as for solar energy concentrators.