Substrate-mediated hyperbolic phonon polaritons in MoO3
Jeffrey Schwartz, Son T. Le, Sergiy Krylyuk, Curt A. Richter, Albert Davydov, Andrea Centrone
Hyperbolic phonon polaritons (HPhPs) are hybrid excitations of light and coherent charge oscillations that exist in strongly optically anisotropic, two-dimensional materials (e.g., MoO3). These polaritons propagate through the material's volume with long lifetimes, enabling novel mid-infrared nanophotonic applications by compressing light to sub-diffraction dimensions. Here, the dispersion relations and HPhP lifetimes (up to ≈ 2.5 ps) in single- crystalline α MoO3 are determined by Fourier analysis of real-space, nanoscale-resolution polariton images obtained with the photothermal induced resonance (PTIR) technique. Measurements of MoO3 crystals deposited on periodic gratings showed longer HPhPs propagation lengths and lifetimes (≈ 2 ×), and lower optical compressions, in suspended regions compared to regions in direct contact with the substrate. Additionally, PTIR data reveal MoO3 subsurface defects, which have a negligible effect on HPhP propagation, as well as polymeric contaminants localized under parts of the MoO3 crystals, which are derived from sample preparation. This work enhances the ability to engineer nanophotonic devices from layered anisotropic materials by leveraging substrate morphology to control polariton propagation.
, Le, S.
, Krylyuk, S.
, , C.
, Davydov, A.
and Centrone, A.
Substrate-mediated hyperbolic phonon polaritons in MoO3, Nanophotonics, [online], https://doi.org/10.1515/nanoph-2020-0640, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=929267
(Accessed August 1, 2021)