Optical response of a strongly anisotropic thin film as a nonmagnetic negative phase velocity material

Abstract

We study the optical response of a strongly anisotropic nonmagnetic material. As a first case, it is considered an anisotropic nonmagnetic thin film (medium 2) sandwiched between medium 1 of refraction index n1 and medium 3 of refraction index n3. As a second case, the anisotropic thin film and medium 3 are interchanged. These geometries correspond to the Kretchmann [E. Kretschmann and H. Raether, Z. Naturforsch. A 23, 2135 (1968); E. Kretschmann, Z. Phys. 241, 313 (1971)] and Otto [A. Otto, Z. Phys. 216, 398 (1968)] attenuated total reflectivity arrays, respectively. Our main goal is to obtain a negative phase velocity propagation. To achieve this we choose an index of refraction n1 >1 and show how the appropriate angle of incidence allows us to induce a negative phase velocity nonmagnetic material. We focused our attention in two distinct regions that emerge in the reflectivity curves when varying the angle of incidence. In the first region, the minima of the reflectivity are interpreted in terms of the coupling of light with the modes at the interface between the anisotropic material and the medium with refraction index n3. In the second region, the structure of the reflectivity is due to the propagation of light in the highly anisotropic material, with negative phase velocity. © 2007 American Institute of Physics.