arXiv subjects

Xuechu Shen

Publications and source records attributed to Xuechu Shen.

3 recordsLinked to original sources

arXiv2019

An Exciton-Polariton Fano Resonance Driven by Second Harmonic Generation

Angle-resolved second harmonic generation (SHG) spectra of ZnO microwires show characteristic Fano resonances in the spectral vicinity of exciton-polariton modes. The output SHG spectra after SHG interacting with exciton polariton shows a resonant enhancement peak accompanied by a suppression dip originating from the constructive and destructive interference respectively. It is demonstrated that the Fano line shape, and thus the Fano asymmetry parameter q, can be tuned by the phase-shift of the two channels. The phase-dependent q was calculated and the model describes our experimental results well. In particular, the phase-to-q relation unveil the crucial information about the dynamics of the system, e.g., defining the line shape of output SHG spectra in a superposition of quantum states.

physics.optics↗

arXiv2010

Room temperature one-dimensional polariton condensate in a ZnO microwire

A cavity-polariton, formed due to the strong coupling between exciton and cavity mode, is one of the most promising composite bosons for realizing macroscopic spontaneous coherence at high temperature. Up to date, most of polariton quantum degeneracy experiments were conducted in the complicated two-dimensional (2D) planar microcavities. The role of dimensionality in coherent quantum degeneracy of a composite bosonic system of exciton polaritons remains mysterious. Here we report the first experimental observation of a one-dimensional (1D) polariton condensate in a ZnO microwire at room temperature. The massive occupation of the polariton ground state above a distinct pump power threshold is clearly demonstrated by using the angular resolved spectroscopy under non-resonant excitation. The power threshold is one order of magnitude lower than that of Mott transition. Furthermore, a well-defined far field emission pattern from the polariton condensate mode is observed, manifesting the coherence build-up in the condensed polariton system.

cond-mat.mes-hall↗

arXiv2008

Direct Observation of Whispering Gallery Mode Polaritons and Their Dispersion in a ZnO Tapered Microcavity

We report direct observation of the strong exciton-photon coupling in ZnO tapered whispering gallery (WG) microcavity at room temperature. By scanning excitations along the tapered arm of ZnO tetrapod using micro-photoluminescence spectrometer with different polarizations, we observed a transition from the pure WG optical modes in the weak interaction regime to the excitonic polariton in the strong coupling regime. The experimental observations are well described by using the plane wave model including excitonic polariton dispersion relation. This provides a direct mapping of the polariton dispersion, and thus a comprehensive picture for coupling of different excitons with differently polarized WG modes.

cond-mat.mes-hall↗