Tuning and Switching a Plasmonic Quantum Dot Sandwich in a Nematic Line Defect

TL;DR

This paper demonstrates a controllable nanoscale platform using liquid crystal defects and laser tweezers to study plasmonic effects on quantum dots, revealing tunable emission properties and exciton-plasmon interactions.

Contribution

It introduces a novel method for precisely controlling quantum dot placement within a plasmonic environment using liquid crystal defects and laser tweezers.

Findings

Quantum dots exhibit photon-antibunching when isolated.

Tight confinement in plasmonic sandwiches decreases quantum dot lifetime.

Multiexciton emission is observed under strong plasmonic confinement.

Abstract

We study the quantum-mechanical effects arising in a single semiconductor core/shell quantum dot controllably sandwiched between two plasmonic nanorods. Control over the position and the sandwich confinement structure is achieved by the use of a linear-trap, liquid-crystal line defect and laser tweezers that push the sandwich together. This arrangement allows for the study of exciton plasmon interactions in a single structure, unaltered by ensemble effects or the complexity of dielectric interfaces. We demonstrate the effect of plasmonic confinement on the photon-antibunching behavior of the quantum dot and its luminescence lifetime. The quantum dot behaves as a single emitter when nanorods are far away from the quantum dot but shows possible multiexciton emission and a significantly decreased lifetime when tightly confined in a plasmonic sandwich. These findings demonstrate that liquid crystal defects, combined with laser tweezers, enable a versatile platform to study plasmonic coupling phenomena in a nanoscale laboratory, where all elements can be arranged almost at will.