Nanoscale imaging and spontaneous emission control with a single nano-positioned quantum dot

Abstract

Plasmonic nanostructures confine light on the nanoscale, enabling ultra-compact optical devices that exhibit strong light-matter interactions. Quantum dots are ideal for probing plasmonic devices because of their nanoscopic size and desirable emission properties. However, probing with single quantum dots has remained challenging because their small size also makes them difficult to manipulate. Here we demonstrate the use of quantum dots as on-demand probes for imaging plasmonic nanostructures, as well as for realizing spontaneous emission control at the single emitter level with nanoscale spatial accuracy. A single quantum dot is positioned with microfluidic flow control to probe the local density of optical states of a silver nanowire, achieving 12 nm imaging accuracy. The high spatial accuracy of this scanning technique enables a new method for spontaneous emission control where interference of counter-propagating surface plasmon polaritons results in spatial oscillations of the quantum dot lifetime as it is positioned along the wire axis.

Optical tracking of nanoscale particles in microscale environments

“…61 Quantum dots often have longer fluorescence lifetimes than organic fluorophores and blink, which is problematic for some tracking applications. 62 Quantum dots have numerous applications, due to the combination of a broad absorption spectrum and a narrow emission spectrum, 46 which enables effective spectral multiplexing.…”

Coupling single emitters to quantum plasmonic circuits

“…Alternatively, Pfaff et al [59] first determined the position of NV centers on a SiO 2 substrate with respect to alignment marks and afterwards fabricated Ag and Al nanowires on top with an electron-beam lithography process. A microfluidic device was used by Ropp et al [60] for positioning and moving QDs around single silver nanowires, enabling them to map out spontaneous emission modifications with a corresponding 12 nm spatial accuracy of the QD.…”

Regioselective Localization and Tracking of Biomolecules on Single Gold Nanoparticles

“…Exploiting this highly confined optical field is crucial, but simultaneously it is also challenging to position the desired molecules or particles accurately at these locations. Different approaches have been employed to achieve selective positioning of the molecules over defined hot spots, such as (i) incorporation of a two‐step electron beam exposure and squeegee process,19 where the first exposure step creates the plasmonic nanostructure and the second step selectively generates openings at hot spots,20 (ii) integrating a microfluidic channel with appropriate flow control,21 (iii) use of atomic force microscopy to manipulate the position of nanoparticles,22 (iv) exploiting material selective surface chemistry for attachment,23, 24 and (v) using multiphoton plasmonic lithography (MPPL) to induce selective polymerization at hot spots due to the enhanced electromagnetic field of the nanostructures 17, 25, 26, 27. Among the above strategies, techniques (i)–(iv) are time‐intensive, prone to inaccuracies, and require prior knowledge of the precise hot spot location.…”