Towards near-infrared polaritonics by a molybdenum diselenide microcavity: converting excitons into polaritons with near-unity photonic fractions

Exciton-polaritons, quasiparticles of half-light and half-matter formed by the coupling of excitons in two-dimensional (2D) semiconductors with photons in microcavities, provide a versatile platform for developing optoelectronic devices and exploring quantum optics at ambient conditions. Currently, near-infrared light sources within the first transmission window (800-900 nm) remain highly in demand for short-range optical transceivers, multimode optical interconnects, and biomedical imaging applications. Here, we report the efficient generation of tunable and near-infrared polariton emission from a clamped monolayer molybdenum diselenide (ML-MoSe₂) microcavity at room temperature and above. Most of the stable exciton emission of ML-MoSe₂ at 780 nm in this microcavity is converted into the widely tunable polariton emission around 820 nm with near-unity photonic fractions. At the detuning energy of -70 meV, a moderate coupling regime is verified with a Rabi splitting energy of 10.2 meV when excitons are resonant with photons at detection angles of ±22°. Moreover, the population and dispersion of exciton-polaritons are modulated by adjusting the excitation power and environmental temperature, respectively. Our work demonstrates an efficient approach to transform native excitonic to desired polaritonic emission in a 2D semiconductor, in favor of developing near-infrared 2D polaritonic devices for short-distance multimode communications and biosensing applications.