Strong coupling of excitons in 2D MoSe2/hBN heterostructure with optical bound states in the continuum

We experimentally demonstrate strong exciton-photon coupling in a MoSe2/hBN heterostructure interfaced with an all-dielectric metasurface supporting high-Q bound states in the continuum. The resulting exciton-polaritons are probed by means of temperature- and angle-resolved reflectivity and photoluminescence. Our findings pave the way towards new-generation nonlinear planar polaritonic devices

Nonlinear polaritons in a monolayer semiconductor coupled to optical bound states in the continuum

Optical bound states in the continuum (BICs) provide a way to engineer very narrow resonances in photonic crystals. The extended interaction time in these systems is particularly promising for the enhancement of nonlinear optical processes and the development of the next generation of active optical devices. However, the achievable interaction strength is limited by the purely photonic character of optical BICs. Here, we mix the optical BIC in a photonic crystal slab with excitons in the atomically thin semiconductor MoSe2 to form nonlinear exciton-polaritons with a Rabi splitting of 27 meV, exhibiting large interaction-induced spectral blueshifts. The asymptotic BIC-like suppression of polariton radiation into the far field toward the BIC wavevector, in combination with effective reduction of the excitonic disorder through motional narrowing, results in small polariton linewidths below 3 meV. Together with a strongly wavevector-dependent Q-factor, this provides for the enhancement and control of polariton–polariton interactions and the resulting nonlinear optical effects, paving the way toward tuneable BIC-based polaritonic devices for sensing, lasing, and nonlinear optics

A benchmarking study of the England and Wales water companies and Sydney Water Corporation Ltd for 1996-97

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