Tunable, Homoepitaxial Hyperbolic Metamaterials Enabled by High Mobility CdO

Advanced Optical Materials, vol. 11

Abstract

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.

Authors 11

1. Angela J. Cleri

   Pennsylvania State University

   Affiliation as printed

   Department of Materials Science and Engineering The Pennsylvania State University University Park PA 16802 USA

   Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802 USA

2. Joshua Ryan Nolen

   City University of New York · Vanderbilt University · CUNY Advanced Science Research Center

   Affiliation as printed

   Interdisciplinary Materials Science Program Vanderbilt University Nashville TN 37212 USA

   Photonics Initiative Advanced Science Research Center City University of New York New York NY 10031 USA

   Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, TN, 37212 USA

   Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, 10031 USA

3. Konstantin G. Wirth Aachen Institute of Physics (IA)

   RWTH Aachen University

   Affiliation as printed

   Institute of Physics (IA) RWTH Aachen University 52062 Aachen Germany

   Institute of Physics (IA), RWTH Aachen University, 52062 Aachen, Germany

4. Mingze He

   Vanderbilt University

   Affiliation as printed

   Department of Mechanical Engineering Vanderbilt University Nashville TN 37212 USA

   Department of Mechanical Engineering, Vanderbilt University, Nashville, TN, 37212 USA

5. Evan L. Runnerstrom

   DEVCOM Army Research Laboratory · United States Army Combat Capabilities Development Command · United States Army · United States Army Research Office

   Affiliation as printed

   DEVCOM US Army Research Laboratory Army Research Office Research Triangle Park NC 27703 USA

   DEVCOM US Army Research Laboratory, Army Research Office, Research Triangle Park, NC, 27703 USA

6. Kyle P. Kelley

   Oak Ridge National Laboratory · Center for Nanophase Materials Sciences

   Affiliation as printed

   Center for Nanophase Materials Science Oak Ridge National Laboratory Oak Ridge TN 37830 USA

   Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge, TN, 37830 USA

7. Joshua Nordlander

   Pennsylvania State University

   Affiliation as printed

   Department of Materials Science and Engineering The Pennsylvania State University University Park PA 16802 USA

   Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802 USA

8. Thomas Taubner Aachen Institute of Physics (IA)

   RWTH Aachen University

   Affiliation as printed

   Institute of Physics (IA) RWTH Aachen University 52062 Aachen Germany

   Institute of Physics (IA), RWTH Aachen University, 52062 Aachen, Germany

9. Thomas G. Folland

   University of Iowa · Vanderbilt University

   Affiliation as printed

   Department of Mechanical Engineering Vanderbilt University Nashville TN 37212 USA

   School of Physics and Astronomy The University of Iowa Iowa City IA 52242 USA

   Department of Mechanical Engineering, Vanderbilt University, Nashville, TN, 37212 USA

   School of Physics and Astronomy, The University of Iowa, Iowa City, IA, 52242 USA

10. Jon‐Paul Maria

    Pennsylvania State University

    Affiliation as printed

    Department of Materials Science and Engineering The Pennsylvania State University University Park PA 16802 USA

    Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802 USA

11. Joshua David Caldwell corresponding

    Vanderbilt University

    Affiliation as printed

    Department of Mechanical Engineering Vanderbilt University Nashville TN 37212 USA

    Department of Mechanical Engineering, Vanderbilt University, Nashville, TN, 37212 USA