Two‐dimensional confined photonic wire resonators – strong light–matter coupling

Abstract

Oxide based Bragg reflector (BR) shells were grown conformally on various curved micro-and nanostructures by means of plasma-enhanced chemical vapor deposition and pulsed laser deposition. The BR shells on circular-cylindrical shaped glassrods exhibit an omnidirectional Bragg stop-band, which was confirmed by spatially resolved ellipsometry. Single free standing hexagonally shaped GaAs and ZnO nanopillars coated with lateral concentric BRs represent two-dimensionally confined photonic-wire resonators (PWR). Spatially resolved PL experiments in dependence on the pillar diameter and the temperature provide strong hints for the ZnO PWR being in the strong-coupling regime. The coupling strength can be estimated to be V ¼ 80 meV, reflecting the enhancement of the excitonpolariton coupling strength due to the reduction of the mode volume in such PWR.Left: Scanning electron microscopy image of a BR coated ZnO nanopillar. The insets show longitudinal and cross-sectional cuts of such a PWR. Right: Spectra of the photoluminescence in dependence of the core cavity diameter d taken from the lateral surface of a ZnO PWR. The mode evolution indicates strong light-matter coupling.

Inhibition and Enhancement of the Spontaneous Emission of Quantum Dots in Micropillar Cavities with Radial-Distributed Bragg Reflectors

“…This relatively low substrate temperature leads to amorphous but smooth DBR layers. The refractive index contrast of the two materials used is about 0.5 (at the investigated wavelengths: n(Al 2 O 3 ) = 1.7 and n(YSZ) = 2.2), 27 leading to a stopband width of the DBR of about 400 meV. With 10 layer pairs the maximum reflectivity amounts to 98.7% at the center of the stopband at 2.2 eV, as deduced from planar samples by means of spectroscopic ellipsometry.…”

“…27 In order to obtain a homogeneous concentric coating of the micropillars, the plasma plume axis was tilted by about 30°with respect to the normal of the rotated substrate. The DBRs consist of 10 pairs of alternating Al 2 O 3 and yttriastabilized zirconia (YSZ) layers.…”

Fabrication of ZnO Nanostructures

“…An alternative way to achieve the strong coupling regime between light and cavity has been presented by Schmidt-Grund et al, who fabricated ZnO core-shell nanowires with multi-layered Al 2 O 3 /YSZ Bragg mirrors as shell layers in order to severely enhance the optical conϐinement [120], see Fig. 2.14.…”

Architecture of nano‐ and microdimensional building blocks

“…[8] it is argued that strong coupling exists between the resonator modes and the ZnO exciton. The estimated coupling strength of 80 meV exceeds that known for the best planar ZnO based resonators [45] at least by a factor of 1.5.…”