An exciton-polariton laser based on biologically produced fluorescent protein

TL;DR

This paper demonstrates room-temperature Bose-Einstein condensation of cavity-polaritons using biologically produced fluorescent protein in microcavities, enabling conventional pumping and advancing organic polariton lasers.

Contribution

It introduces a novel biologically based organic material for polariton BEC, overcoming previous limitations and enabling room-temperature operation with standard nanosecond pumping.

Findings

Room-temperature BEC achieved with eGFP in microcavities.

Distinct threshold and long-range coherence observed.

Second threshold indicating photon lasing and thermalization.

Abstract

Under adequate conditions, cavity-polaritons form a macroscopic coherent quantum state, known as Bose-Einstein condensate (BEC). Compared to Wannier-Mott excitons in inorganic semiconductors, the localized Frenkel excitons in organic emitter materials show weaker interaction but stronger coupling, which recently enabled the first realization of BEC at room temperature. However, this required ultrafast optical pumping which limits the applications of organic BECs. Here, we demonstrate room-temperature BEC of cavity-polaritons in simple laminated microcavities filled with the biologically produced enhanced green fluorescent protein (eGFP). The unique molecular structure of eGFP prevents exciton annihilation even at high excitation densities, thus facilitating BEC under conventional nanosecond pumping. BEC is clearly evidenced by a distinct threshold, an interaction-induced blueshift of the condensate, long-range coherence and the presence of a second threshold at higher excitation density which is associated with the onset of photon lasing and results from thermalization of the exciton reservoir.