Strong coupling between excitons in transition metal dichalcogenides and optical bound states in the continuum

S K Sychev,K L Koshelev,A A Bogdanov,I V Iorsh,Z F Sadrieva

doi:10.1088/1742-6596/1124/5/051056

Abstract

Being motivated by recent achievements in the rapidly developing fields of optical bound states in the continuum (BICs) and excitons in monolayers of transition metal dichalcogenides, we analyze strong coupling between BICs in Ta2O5 periodic photonic structures and excitons in WSe2 monolayers. We demonstrate that giant radiative lifetime of BICs allows to engineer the exciton-polariton lifetime enhancing it three orders of magnitude compared to a bare exciton. We show that maximal lifetime of hybrid light-matter state can be achieved at any point of k-space by shaping the geometry of the photonic structure.

Highlights

Monolayers of transition metal dichalcogenides (TMDCs) are a certain class of postgraphene two-dimensional materials [1], attracting vast research interest in recent years
These structures support excitons characterized by both large binding energies and sufficiently large Bohr radii [3], giving a rise to the existence of a strong excitonic response at room temperature and providing strong optical nonlinearity due to the excitonexciton interactions [4]. Another important property of the TMDC excitons is the large oscillator strength leading to the substantial exciton-photon interaction in these structures. These properties allow for the observation of the so-called strong coupling regime, leading to the emergence of exciton polaritons [5] at room temperatures in structures comprising a TMDC monolayer and an optical cavity
Strong coupling of TMDC excitons with light was observed in structures resembling conventional microcavities, where the monolayer was sandwiched between two Bragg mirrors [10,11,12,13]

Summary

Rapid Communications

V. Iorsh1 1ITMO University, 197101 St. Petersburg, Russian Federation. Being motivated by recent achievements in the rapidly developing fields of optical bound states in the continuum (BICs) and excitons in monolayers of transition metal dichalcogenides, we analyze strong coupling between BICs in Ta2O5 periodic photonic structures and excitons in WSe2 monolayers. We demonstrate that the giant radiative lifetime of a BIC allows us to engineer the exciton-polariton lifetime, enhancing it by two orders of magnitude compared to a bare exciton. We show that the maximal lifetime of a hybrid light-matter state can be achieved at any point of k space by shaping the geometry of the photonic structure. Our findings open a different route for the realization of moving exciton-polariton condensates with a nonresonant pump and without Bragg mirrors, which is of paramount importance for polaritonic devices

INTRODUCTION

UP mode bare PhC eigenmode

CONCLUSION