Tunable, Homoepitaxial Hyperbolic Metamaterials Enabled by High Mobility CdO
Abstract
Propagating light exhibits hyperbolicity in strongly anisotropic materials where the principal components of the dielectric tensor are opposite in sign. While hyperbolicity occurs naturally in anisotropic polar dielectrics, wherein optical phonons along orthogonal crystal axes are nondegenerate, such optical anisotropy can also be engineered in hyperbolic metamaterials (HMMs): thin film superlattices of alternating dielectric and metallic layers. Contrasted with the severely limited tunability of natural hyperbolic materials, the hyperbolic behavior of HMMs can be tailored significantly both through superlattice design and material selection. However, so far HMMs have suffered from high optical losses, hindering their performance. In this report, broadly tunable (λ = 2–5 µm) Type I and II hyperbolic modes with low losses (quality (Q)‐factors up to 19.7) are observed through attenuated total reflectance measurements of monolithic, homoepitaxial superlattices of high‐ and low‐doped cadmium oxide (CdO). Further, the low losses offered by CdO enable the first demonstration of real‐space imaging of hyperbolic plasmon polaritons in nanoresonators by scattering‐type scanning near‐field optical microscopy—previously only possible for hyperbolic phonon polariton materials. Tunable, low‐loss CdO HMMs promise designability for applications such as on‐chip photonics, super‐resolution imaging (hyperlensing), enhanced emission, novel emitter designs, and possibly quantum nanophotonic and time variant metasurfaces.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 09, 2022
- Source ID
- 10.1002/adom.202202137
Entities
People
- Angela Cleri
- Evan L. Runnerstrom
- J. Ryan Nolen
- Jon‐paul Maria
- Joshua D Caldwell
- Joshua Nordlander
- Konstantin G. Wirth
- Kyle Kelley
- Ming-Ze He
- Thomas Folland
- Thomas Taubner
Organizations
- City University of New York
- German Research Foundation
- Oak Ridge National Laboratory
- Office of Naval Research
- Pennsylvania State University
- RWTH Aachen University
- United States Army Research Laboratory
- University of Iowa
- Vanderbilt University