Coupled surface plasmon–phonon polariton nanocavity arrays for enhanced mid-infrared absorption


Resonant optical cavities are essential components in mid-infrared applications. However, typical film-type cavities require multilayer stacks with a micron-thick spacer due to mid-infrared wavelengths, and their performance is limited by narrow frequency tunability and angular sensitivity. We propose and experimentally demonstrate the subwavelength-scale (≈λ0/150) resonant nanocavity arrays that enhance the absorption spectrum of the device in the mid-infrared (10–12 microns) via excitation of coupled surface plasmon–phonon polaritons. The proposed metal–insulator–polar dielectric (gold–silicon–silicon carbide) structure supports a guided mode of the coupled surface polaritons in the lateral direction while vertically confining the mid-infrared wave within the 80 nm thick dielectric spacer. In particular, the subwavelength-scale (≈λ0/10) gratings are imposed to form Fabry–Pérot cavity arrays displaying angle-insensitive and frequency-tunable absorption of up to 80% of the optical power in the mid-infrared. Our work should benefit diverse mid-infrared applications and novel designs of polariton-based photonic devices.


© 2022 the author(s), published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 International License.


Coupled Plasmon-Phonon Polariton Mode, Enhanced Optical Power Absorption, Fabry–Pérot Cavity Array, Propagating Surface Phonon Polaritons


Kachiraju, S., Nekrashevich, I., Ahmad, I., Farooq, H., Chang, L., Kim, S. & Kim, M. (2022). Coupled surface plasmon–phonon polariton nanocavity arrays for enhanced mid-infrared absorption. Nanophotonics, 11(20), 4489-4498.