Thermalization of Fluorescent Protein Exciton–Polaritons at Room Temperature. Issue 15 (6th March 2022)

• Record Type: Journal Article
• Authors: Satapathy, Sitakanta; Liu, Bin; Deshmukh, Prathmesh; Molinaro, Paul M.; Dirnberger, Florian; Khatoniar, Mandeep; Koder, Ronald L.; Menon, Vinod M.
• Is Part Of: Advanced materials. Volume 34:Issue 15(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-06
• Subjects: exciton–polaritons -- fluorescent proteins -- optical cavities -- polariton condensation -- strong coupling -- thermalization; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202109107
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Fluorescent proteins (FPs) have recently emerged as a serious contender for realizing ultralow threshold room temperature exciton–polariton condensation and lasing. This contribution investigates the thermalization of FP microcavity exciton–polaritons upon optical pumping under ambient conditions. Polariton cooling is realized using a new FP molecule, called mScarlet, coupled strongly to the optical modes in a Fabry–Pérot cavity. Interestingly, at the threshold excitation energy (fluence) of ≈9 nJ per pulse (15.6 mJ cm −2 ), an effective temperature is observed, T eff ≈ 350 ± 35 K close to the lattice temperature indicative of strongly thermalized exciton–polaritons at equilibrium. This efficient thermalization results from the interplay of radiative pumping facilitated by the energetics of the lower polariton branch and the cavity Q ‐factor. Direct evidence for dramatic switching from an equilibrium state into a metastable state is observed for the organic cavity polariton device at room temperature via deviation from the Maxwell–Boltzmann statistics at k ‖ = 0 above the threshold. Thermalized polariton gases in organic systems at equilibrium hold substantial promise for designing room temperature polaritonic circuits, switches, and lattices for analog simulation. Abstract : Strong exciton–photon coupling is demonstrated using a red fluorescent protein "mScarlet" integrated with a microcavity. The strongly coupled exciton–polariton system demonstrates nonlinear response along with thermalization and cooling at room temperature. The effective temperature, T eff ≈ 350 K close to the lattice temperature indicates strongly thermalized exciton–polaritons.