Room-Temperature Exciton Polariton Condensate and Lasing in Emergent Semiconductor Materials

熊启华 教授
2019-10-18 (周五) 10:00

Microcavity exciton polaritons are part-light, part-matter strongly interacting Bosonic quasiparticles derived from strong light-matter coupling between excitons and microcavity photons, which have shown tremendous potential in quantum optics, ultrafast polaritonic switching and topological polaritonics. However, previous investigations are largely limited in pedagogic III-V GaAs quantum wells operating at only liquid helium temperatures constrained by the small exciton binding energy. Some organic materials show promise in exciton polaritonics at room temperature, nonetheless they usually suffer from large threshold density and weak nonlinearity due to the Frenkel exciton nature. In this talk, I will introduce our recent progress in realizing exciton polariton condensate and lasing in a few halide perovskite materials and atomically thin transition metal dichalcogenides. These effects are usually unambiguously evidenced by superlinear power dependence, macroscopic ground state occupation, blueshift of the ground state emission, and the build-up of long-range spatial coherence. Furthermore, we have shown the optical manipulating of such condensate by ultrafast propagation in 1D waveguides and 1D artificial polariton lattices. Interesting, modulated by deep periodic potentials, the polariton lattice exhibits a large forbidden bandgap opening up to 13.3 meV, which are at least 10 times larger than previous systems. Above a critical density, we observe exciton polariton condensation into py orbital states with long-range spatial coherence at room temperature. My final part of talk will discuss the first realization of ultralow threshold continuous-wave pumped polariton condensate in monolayer WS2 multiple quantum well cavity, with a Rabi splitting of ~37 meV and ~ 0.5 nW threshold. A long-range spatial coherence is identified across the entire condensate at room temperature. Our work advocates the room-temperature polaritonics with considerable promises in a wide range of applications, for instance electrically pumped polariton lasing and artificial polariton lattices for quantum simulator at room temperature.



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  5. Q. Zhang, et al., “Room-temperature near-infrared high-Q perovskite whispering-gallery planar nanolasers”, Nano Lett. 14, 5995-6001 (2014)