Spontaneously coherent orbital coupling of counterrotating exciton polaritons in annular perovskite microcavities

Exciton-polariton condensation is regarded as a spontaneous macroscopic quantum phenomenon with phase ordering and collective coherence.By engineering artificial annular potential landscapes in halide perovskite semiconductor microcavities,we experimentally and theoretically demonstrate the room-temperature spontaneous formation of a coherent superposition of exciton-polariton orbital states with symmetric petal-shaped patterns in real space,resulting from symmetry breaking due to the anisotropic effective potential of the birefringent perovskite crystals.The lobe numbers of such petal-shaped polariton condensates can be precisely controlled by tuning the annular potential geometry.These petal-shaped condensates form in multiple orbital states,carrying locked alternating nphase shifts and vortex-anti vortex superposition cores,arising from the coupling of counterrotating exciton-polaritons in the confined circular waveguide.Our geometrically patterned microcavity exhibits promise for realizing room-temperature topological polaritonic devices and optical polaritonic switches based on periodic annular potentials.

Perovskite polariton parametric oscillator

Optical parametric oscillators(OPOs)have been widely applied in spectroscopy,squeezed light,and correlated photons,as well as quantum information.Conventional OPOs usually suffer from a high power threshold limited by weak high-order nonlinearity in traditional pure photonic systems.Alternatively,polaritonic systems based on hybridized exciton–photon quasi-particles exhibit enhanced optical nonlinearity by dressing photons with excitons,ensuring highly nonlinear operations with low power consumption.We report an on-chip perovskite polariton parametric oscillator with a low threshold.Under the resonant excitation at a range of angles,the signal at the ground state is obtained,emerging from the polariton-polariton interactions at room temperature.Our results advocate a practical way toward integrated nonlinear polaritonic devices with low thresholds.

Tunable ultraviolet to deep blue light emission from sulfur nanodots fabricated by a controllable fission-aggregation strategy

Bright tunable light emission in the short wavelength range from sulfur nanodots was demonstrated with a photoluminescence quantum yield(PLQY)of up to 59.4%.A fission-aggregation mechanism was proposed for the formation of sulfur nanodots with desired performances.This synthetic strategy allowed for simultaneous size control from 3.2 to 5.6 nm,thus tuning the emission color from ultraviolet(UV)to deep blue(342±430 nm),and for the suppression of unwanted nonradiative recombination centers and deep level emission.The luminescence mechanism and quantum confinement effect of the synthesized sulfur nanodots were investigated by optical spectroscopy and theoretical calculations.These results show promise toward the application of sulfur nanodots in UV optoelectronics,biomedical treatments,and sterilization.