Strong coupling beyond the high-Q limit and linewidth narrowing in a multiexciton planar microcavity
Phys. Rev. Applied 25, 044067 – Published 23 April, 2026
DOI: https://doi.org/10.1103/8d5h-8m97
Abstract
We systematically study the linewidths of multilevel exciton-polariton modes as a function of the detuning in a planar hybrid microcavity (MC) with low quality factor (Q ∼ 300) operating in the linear optical response regime. Using optical reflectivity, we observe that, counterintuitively, the linewidths of the polariton modes undergo a pronounced spectral narrowing as detuning is reduced. By benchmarking the experimental results against three commonly used constant-loss theoretical descriptions, we find that this behavior is only partially reproduced, highlighting limitations of conventional strong-coupling models when applied to nonstandard MC architectures. Our results suggest that frequency-dependent self-energy effects or correlated dissipation mechanisms, typically neglected in simplified treatments, may play an important role. These observations indicate that strong light-matter coupling with narrow polariton lines can be achieved in hybrid low-Q MCs through appropriate loss engineering, providing an alternative design pathway complementary to conventional high-Q approaches.
