Fabrication of embedded plasmonic antennas for nano-optomechanics with 2D materials*

Suspension of 2D materials over an antenna that is embedded in a dielectric cavity presents new paradigms for nanophotonic engineering and nano-optomechanics in 2D materials with applications that span from on-demand single-photon emitters to low-temperature, high Q-factor optomechanical resonators. The hybrid optomechanic and plasmonic architecture can capitalize on the combined effects of strain engineering and nanoplasmonics. Here, the fabrication of metallic antennas embedded in an SiO2 dielectric cavity is described. The method is a modified optical lithography process occurring on the top of a SiO2 film, giving rise to antennas with 1-3 µm base diameters. The proof-of-concept fabrication process demonstrates how the height of the embedded antennae can be tuned with nanometer precision and reveals the next steps for further miniaturization of the antenna and the cavity using electron-beam lithography. Such precise control and miniaturization are crucial for future use of the structures to demonstrate, for example, strong-coupling between plasmons and excitons and nano-optomechanic schemes with 2D materials that aim to use the dipole field between the antennae and a 2D heterostructure to optically control the funneling of excitons and modulate quantum emission phenomena.