Enhancement of two photon processes in quantum dots embedded in subwavelength metallic gratings

TL;DR

This paper demonstrates significant enhancement of two-photon absorption and upconversion efficiency in quantum dots embedded in metallic nanoslit arrays, leveraging resonant electromagnetic field enhancements for improved nonlinear optical processes.

Contribution

It introduces a hybrid device structure that significantly boosts two-photon processes in quantum dots through resonant field enhancement in subwavelength metallic gratings.

Findings

Over 20-fold increase in two-photon absorption

Identification of polarization-dependent high field regions

Potential for designing efficient nonlinear optical devices

Abstract

We show a large enhancement of two-photon absorption processes in nanocrystal quantum dots and of light upconversion efficiency from the IR to the near-IR spectral regime, using a hybrid optical device in which near-IR emitting InAs quantum dots were embedded on top a metallic nanoslit array. The resonant enhancement of these nonlinear optical processes is due to the strong local electromagnetic field enhancements inside the nanoslit array structure at the extraordinary transmission resonances. A maximal two-photon absorption enhancement of more than 20 was inferred. Different high field regions were identified for different polarizations, which can be used for designing and optimizing efficient nonlinear processes in such hybrid structures. Combining nanocrystal quantum dots with subwavelength metallic nanostructures is therfore a promising way for a range of possible nonlinear optical devices.