Using the ferroin-catalyzed Belosov-Zhabotinsky (BZ) reaction with the addition of an activating reactant in a reaction-diffusion system, we experimentally studied the competition between target waves and spiral waves when the system was in an oscillatory state. We found that when the period of background oscillation is smaller than that of spiral waves, target waves automatically appear in the reaction medium despite of the presence of spiral waves. The target waves compete with spiral waves and eventually win over the spirals, driving them out of the reaction medium. We also carried out numerical simulations using a modified Oregonator model. Our simulation results qualitatively agree with the experimental observations.
Room-temperature polariton lasing is achieved in GaN microrods grown by metal-organic vapor phase epitaxy. We demonstrate a large Rabi splitting (Ω = 2g0) up to 162 meV, exceeding the results from both the state-of-the-art nitride-based planar microcavities and previously reported GaN microrods. An ultra-low threshold of 1.8 kW/cm2 is observed by power-dependent photoluminescence spectra, with the linewidth down to 1.31 meV and the blue shift up to 17.8 meV. This large Rabi splitting distinguishes our coherent light emission from a conventional photon lasing, which strongly supports the preparation of coherent light sources in integrated optical circuits and the study of exciting phenomena in macroscopic quantum states.
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