Cooperative emission mediated by cooperative energy transfer to a plasmonic antenna

TL;DR

This paper presents a comprehensive theory of cooperative emission via energy transfer to plasmonic antennas, showing how emission scales with ensemble size and can be tuned, with implications for controlling light emission.

Contribution

It introduces explicit expressions for cooperative Purcell and enhancement factors for arbitrary plasmonic structures, and demonstrates linear scaling of CET rate with emitter number in specific configurations.

Findings

CET rate scales linearly with the number of quantum emitters in certain regions.

The radiated power spectrum maintains plasmon resonance lineshape with amplitude scaling.

The cooperative Purcell factor has a universal form independent of system size.

Abstract

We develop a theory of cooperative emission mediated by cooperative energy transfer (CET) from an ensemble of quantum emitters (QE) to plasmonic antenna at a rate equal to the sum of individual QE-plasmon energy transfer rates. If the antenna radiation efficiency is sufficiently high, the transferred energy is radiated away at approximately the same cooperative rate that scales with the ensemble size. We derive explicit expressions, in terms of local fields, for cooperative Purcell factor and enhancement factor for power spectrum valid for plasmonic structures of any shape with characteristic size smaller than the radiation wavelength. The radiated power spectrum retains the plasmon resonance lineshape with overall amplitude scaling with the ensemble size. If QEs are located in a region with nearly constant plasmon local density of states (LDOS), e.g., inside a plasmonic nanocavity, we demonstrate that the CET rate scales linearly with the number of excited QEs, consistent with the experiment, and can be tuned in a wide range by varying the excitation power. For QEs distributed in an extended region saturating the plasmon mode volume, we show that the cooperative Purcell factor has universal form independent of the system size. The CET mechanism incorporates the plasmon LDOS enhancement as well, giving rise to possibilities of controlling the emission rate beyond field enhancement limits.