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

Nonlinear route to intrinsic Josephson oscillations in spinor cavity-polariton condensates

This work was supported by the Russian Science Foundation (Grant No. 14-12-01372).The intrinsic Josephson effect is observed in a two-component polariton condensate in a strained planar microcavity under a resonant pulsed excitation such that only one of the two linearly polarized eigenstates is pumped from the outside. On reaching the threshold density, the polariton-polariton interaction involves a spontaneous breaking of the symmetry between spin-up and spin-down polaritons. As a result, the condensate acquires nearly circular polarization while the pump is strong and then passes to the Josephson oscillation regime since the pump weakens.Publisher PDFPeer reviewe