Enhanced sensing of molecular optical activity with plasmonic nanohole arrays

TL;DR

This paper demonstrates that plasmonic nanohole arrays can significantly enhance the optical detection of molecular chirality at nanoscale volumes, with spatial resolution of tens of nanometers, primarily driven by near-field effects.

Contribution

It introduces a model showing over tenfold enhancement in optical activity detection using metal hole arrays filled with chiral materials, emphasizing the role of plasmonic near fields.

Findings

Activity enhancement exceeds an order of magnitude.

Spatial resolution of chirality detection is a few tens of nanometers.

Detection sensitivity is mainly due to near-field enhancement, not array shape.

Abstract

Prospects of using metal hole arrays for the enhanced optical detection of molecular chirality in nanosize volumes are investigated. Light transmission through the holes filled with an optically active material is modeled and the activity enhancement by more than an order of magnitude is demonstrated. The spatial resolution of the chirality detection is shown to be of a few tens of nanometers. From comparing the effect in arrays of cylindrical holes and holes of complex chiral shape, it is concluded that the detection sensitivity is determined by the plasmonic near field enhancement. The intrinsic chirality of the arrays due to their shape appears to be less important.