Detecting mid-infrared light by molecular frequency upconversion with dual-wavelength hybrid nanoantennas

TL;DR

This paper demonstrates a method to detect mid-infrared light by converting it to visible light using plasmonic nanoantennas, enabling sensitive, room-temperature infrared detection and spectroscopy at the single-molecule level.

Contribution

It introduces a novel dual-wavelength hybrid nanoantenna system that achieves high-efficiency frequency upconversion of MIR light via surface-enhanced Raman scattering.

Findings

Achieved >10^10 enhancement in upconversion efficiency.

Demonstrated >200% amplification of anti-Stokes emission with MIR pump.

Detected MIR signals at powers as low as 1 μW/μm^2 at room temperature.

Abstract

Coherent interconversion of signals between optical and mechanical domains is enabled by optomechanical interactions. Extreme light-matter coupling produced by confining light to nanoscale mode volumes can then access single mid-infrared (MIR) photon sensitivity. Here we utilise the infrared absorption and Raman activity of molecular vibrations in plasmonic nanocavities to demonstrate frequency upconversion. We convert {\lambda}~10 {\mu}m incoming light to visible via surface-enhanced Raman scattering (SERS) in doubly-resonant antennas that enhance upconversion by >10^10. We show >200% amplification of the SERS antiStokes emission when a MIR pump is tuned to a molecular vibrational frequency, obtaining lowest detectable powers ~1 {\mu}W/{\mu}m^2 at room temperature. These results have potential for low-cost and large-scale infrared detectors and spectroscopic techniques, and bring single-molecule sensing into the infrared