Exciton-photon interaction in semiconductor hexagonal wire structures : from Hermitian to non-Hermitian photonics

Abstract

Since group III-nitride based semiconductors yield bright emission from the visible to UV range at room temperature, we can easily access as LED and laser in our life. However, conventional planar structures are limited to fabricate low dimensional quantum structures and cavity structures, which are essential factors for the research of quantum photonics. In this dissertation, we exploited a pencil-shaped hexagonal microwire structure to apply for the research of quantum photonics from Hermitian to non-Hermitian. Exploiting the pencil-shaped wire structures as a backbone for the subsequent growth, the well-controlled quantum wire structures are orthogonally arranged with dual-wavelength and applied for the polarization and wavelength entangled compact light sources. Using the cross-section of the hexagonal wire as a microcavity generating whispering gallery modes, we observed the hybrid nature of excitons and photons (exciton-polariton) and manipulated the polaritonic condensate at room temperature. Besides, employing the substrate engineering, we obtained non-Hermitian degeneracies in PT symmetry by the coupled upward- and downward-triangular whispering gallery polariton pair to exploit the reversing effect of loss as gain, counterintuitively. We expect our pencil-shaped hexagonal microwire structures can ignite a new platform for semiconductor-based quantum photonic operating at room temperature.