Non-resonant feeding of photonic crystal nanocavity modes by quantum dots

TL;DR

This study investigates how photons are non-resonantly fed into photonic crystal nanocavity modes from quantum dots, revealing temperature-dependent asymmetries and multi-exciton contributions to the emission process.

Contribution

It provides experimental evidence of non-resonant photon feeding mechanisms in quantum dot-cavity systems, highlighting the role of multi-exciton states and temperature effects.

Findings

Asymmetry in emission intensity at low temperatures depending on exciton-cavity detuning.

Photon feeding occurs from multi-exciton transitions, not just single excitons.

Temperature influences phonon-assisted emission symmetry.

Abstract

We experimentally probe the non-resonant feeding of photons into the optical mode of a two dimensional photonic crystal nanocavity from the discrete emission from a quantum dot. For a strongly coupled system of a single exciton and the cavity mode, we track the detuning-dependent photoluminescence intensity of the polariton peaks at different lattice temperatures. At low temperatures we observe a clear asymmetry in the emission intensity depending on whether the exciton is at higher or lower energy than the cavity mode. At high temperatures this asymmetry vanishes when the probabilities to emit or absorb a phonon become similar. For a different dot-cavity system where the cavity mode is detuned by \Delta E>5 meV to lower energy than the single exciton transitions emission from the mode remains correlated with the quantum dot as demonstrated unambiguously by cross-correlation photon counting experiments. By monitoring the temporal evolution of the photoluminescence spectrum, we show that feeding of photons into the mode occurs from multi-exciton transitions. We observe a clear anti-correlation of the mode and single exciton emission; the mode emission quenches as the population in the system reduces towards the single exciton level whilst the intensity of the mode emission tracks the multi-exciton transitions.