Calibrating and Controlling the Quantum Efficiency Distribution of Inhomogeneously Broadened Quantum Rods by Using a Mirror Ball

Abstract

We demonstrate that a simple silver coated ball lens can be used to accurately measure the entire distribution of radiative transition rates of quantum dot nanocrystals. This simple and cost-effective implementation of Drexhage's method that uses nanometer-controlled optical mode density variations near a mirror, not only allows an extraction of calibrated ensemble-averaged rates, but for the first time also to quantify the full inhomogeneous dispersion of radiative and non radiative decay rates across thousands of nanocrystals. We apply the technique to novel ultrastable CdSe/CdS dot-in-rod emitters. The emitters are of large current interest due to their improved stability and reduced blinking. We retrieve a room-temperature ensemble average quantum efficiency of 0.87 ± 0.08 at a mean lifetime around 20 ns. We confirm a log-normal distribution of decay rates as often assumed in literature, and we show that the rate distribution-width, that amounts to about 30% of the mean decay rate, is strongly dependent on the local density of optical states.

Determining the internal quantum efficiency of shallow-implanted nitrogen-vacancy defects in bulk diamond

“…Therefore, instead of moving the spherical mirror to change the NV defect-mirror distance, we observed different areas within the NV-implanted region of the diamond to study the effect of LDOS variation on the decay rate [23]. This allowed us keeping the spherical mirror at a fixed position on top of the diamond sample, and we moved the diamond sample together with the mirror as a whole during measurements with the aid of a piezo stage.…”

“…The same scheme, but with a number of improvements and modifications, has been used to characterize different types of quantum emitters: single molecules [18][19][20], self-assembled [21,22] and colloidal [23] quantum dots, as well as NV defects in diamond nanocrystals [15]. In our work, we use an experimental approach that was first suggested in [19] and later modified for well calibrated measurements [15,23]. The approach consists in using a scanning metallic mirror, so that the distance between an emitter and the mirror can be changed in the course of the experiment, without the need to fabricate a new sample.…”

The local density of optical states of a metasurface

“…1(b) . The relative lifetimes oscillate as a function of distance with a periodicity of about λ /2, as encountered in typical Drexhage-type experiments 2 3 29 30 . Comparing the electric versus magnetic lattices, we note that the oscillations in lifetime are π out of phase.…”

Control of the external photoluminescent quantum yield of emitters coupled to nanoantenna phased arrays

“…We attribute the large A tot at h ex ¼ 4. 5 and u ex ¼ 0 to an increased absorption in the dye layer resulting from the coupling of the incident light to quasi-guided modes, and the peaks of A tot observed at ðh ex ; u ex Þ ¼ ð13…”