Tunable polariton absorption of distributed feedback microcavities at room temperature

TLDR

Strong coupling between excitons and photons at normal incidence forms cavity polaritons in Fabry‑Perot semiconductor microcavities. A fourth‑order distributed‑feedback microcavity is fabricated by spin‑coating self‑organized (C₆H₅C₂H₄NH₃)₂PbI₄ multiple quantum wells onto a 0.7 µm‑period corrugated quartz substrate. The device exhibits well‑separated, tunable polariton absorption at room temperature, with anticrossing dips that shift by changing grating period or incident angle and a mode splitting of up to 100 meV due to the material’s large excitonic oscillator strength.

Abstract

We have demonstrated well-separated tunable polariton absorption for a semiconductor-cavity composite system in transmission measurements at room temperature. A distributed feedback microcavity of the fourth order is fabricated by spin coating a self-organized inorganic/organic multiple quantum wells, $({\mathrm{C}}_{6}{\mathrm{H}}_{5}{\mathrm{C}}_{2}{\mathrm{H}}_{4}{\mathrm{NH}}_{3}{)}_{2}{\mathrm{PbI}}_{4}$, on a corrugated quartz substrate with a period of about $0.7 \ensuremath{\mu}\mathrm{m}$. By changing the grating period or the incident angle, the absorption dips exhibit anticrossing behavior. Owing to the large excitonic oscillator strength of the material, the polariton mode splitting is as large as $100 \mathrm{meV}$ even at room temperature. At the normal incidence, an exciton and a light form a strongly coupled standing wave, which corresponds to a cavity polariton in Fabry-Perot semiconductor microcavities.