Optomechanical frequency upconversion in nanocavities

Benefiting from the plasmonic resonance capable of nanoscale light confinement, metallic gap nanoantennas (and their coupling with low-dimensional materials) have been demonstrated a powerful platform to research a variety of novel phenomena with unprecedented sensitivity, including, plasmon-exciton strong coupling, enhanced optical nonlinearities and molecular cavity optomechanics.

In this project, we are developing a molecular platform coupled with a dual resonant plasmonic antenna to experimentally realize the efficient terahertz-to-visible frequency upconversion at the nanoscale (Fig. 1). As proposed theoretically, the incoming mid-infrared (MIR) light (~9 um) is converted to intermediate vibrational energy of the molecules via plasmon-enhanced IR absorption. Meanwhile, converted vibrational mode is summed with a visible pumping light through plasmon-enhanced Raman (Anti-Stokes) scattering mediated by optomechanical coupling. The experimental demonstration of such sum frequency generation would open exciting possibilities for the coherent detection MIR signals at room temperature, with superior sensitivity, lower noise and reduced footprint. This would show significant impact on sensing, imaging, spectroscopy, and communication technologies.

Postdoc : Wen Chen

Collaboration: Alejandro Martinez, Univ. Poli. Valencia, Spain

References: [1] P. Roelli et al. Phys. Rev. X (2020) https://journals.aps.org/prx/abstract/10.1103/PhysRevX.10.031057

Funding: Horizon 2020 FET-Open THOR

Fig. 1: Concept of optomechanical THz/IR-to-visible frequency upconversion, Ref. [1]