Two-photon up-conversion affected by inter-molecule correlations near metallic nanostructure

TL;DR

This paper explores how inter-molecule correlations near a metallic nanostructure can enhance two-photon up-conversion efficiency, overcoming limitations of multiple molecules sharing photon energy, by controlling inter-molecule coupling.

Contribution

It extends previous single-molecule models to multiple molecules, demonstrating that controlling inter-molecule coupling can increase up-conversion probability without increasing light power.

Findings

Inter-molecule coupling can be tuned to improve up-conversion efficiency.

Multiple molecules generally decrease up-conversion probability due to shared photon energy.

Proper control of inter-molecule interactions overcomes efficiency reduction.

Abstract

We investigate an efficient two-photon up-conversion process in more than one molecule coupled to an optical antenna. In the previous work [Y. Osaka et al., PRL 112, 133601 (2014)], we considered the two-photon up-conversion process in a single molecule within one-dimensional input-output theory, and revealed that controlling the antenna-molecule coupling enables the efficient up-conversion with radiative loss in the antenna suppressed. In this work, aiming to propose a way to enhance the total probability of antenna-photon scattering, we extend the model to the case of multiple molecules. In general, the presence of more than one molecule decreases the up-conversion probability because they equally share the energy of the two photons. However, it is shown that we can overcome the difficulty by controlling the inter-molecule coupling. Our result implies that, without increasing the incident photon number (light power), we can enlarge the net probability of the two-photon up-conversion.