Realization of an all-optically controlled dynamic superlattice for exciton–polaritons

Abstract

Exciton-polaritons, formed by the strong coupling between excitons and cavity-confined photons, are the building blocks of polaritonic devices. In this work, we report experimental realization of an all-optically controlled dynamic superlattice for polaritons working in the ultraviolet wavelength range at room temperature. The optical superlattice was realized on a one-dimensional (1D) ZnO microrod using an array of periodically arranged laser spots. Polaritonic mini-band features were clearly observed by both momentum- and real-space imaging spectroscopy. By controlling the periodicity of the laser spots, we demonstrated that the band structures of polaritons can be well controlled by external lasers. Theoretically, by extending the Kronig-Penney model to the polariton system, we calculated the polaritonic mini-bands and found it to be in good agreement with our experimental observations. By imaging the polariton flow in real space, the lifetime of polaritons and their relationship with their exitonic fractions were also extracted. The polaritonic superlattices demonstrated in this work are fully reconfigurable and optically controlled, and our results could thus stimulate the development of polaritonic all-optical devices.

Polariton–Polariton Interactions Revealed in a One-dimensional Whispering Gallery Microcavity

“…They have very smooth hexagonal cross sections which support WG resonant modes for light fields, as shown schematically in Figure b. Exciton-polaritons are formed due to the strong coupling between these WG modes and the excitonic states. , A typical angle-resolved photoluminescence (PL) image of such microrods is shown in Figure b. The formation of polaritons is evidenced by the excellent agreement between the emission pattern and the theoretical dispersion (dashed curve) fitted using the coupled-oscillator model.…”

“…While their photonic component makes them extremely light particles, their inherited excitonic component gives them the ability to interact with other charge carriers via Coulomb forces. Nowadays, it is generally known that these polaritonic Coulomb interactions essentially govern the dynamics and optical properties of exciton-polaritons. , Many of the fascinating phenomena, such as quantized vortices and tunable magnetic alignments, − are closely related to the polariton–polariton interactions. A comprehensive understanding of such polaritonic interactions is thus of fundamental importance.…”

Relaxation Oscillations of an Exciton-polariton Condensate Driven by Parametric Scattering

“…The samples we used are one-dimensional ZnO microrods grown by chemical vapor deposition method. Having smooth facets and hexagonal cross-sections, such microrods form natural whispering gallery (WG) microcavities for the confinement of light field [17,24,37,38]. The intrinsically large excitonic binding energy (∼ 60 meV at room temperature) and oscillator strength make them a promising testing bed for experimental studies of polaritonics, as demonstrated in our previous work [17,24,39].…”

Polariton lasing and energy-degenerate parametric scattering in non-resonantly driven coupled planar microcavities

“…Such a system has so far been realized in a set of vertically coupled planar microcavities [21,28] or a semiconductor microrod. [29][30][31][32] Offering a high degree of tunability, vertically coupled microcavities have been studied mostly in the linear regime, [23,28,[33][34][35][36][37] while the non-linear regime was addressed in the exclusive context of resonantly driven parametric scattering. [20,21] In particular, such fundamental effects as polariton condensation and lasing, or parametric polariton scattering under non-resonant excitation, have so far not been observed and studied in a vertically coupled, planar microcavity system.…”