• Advanced Photonics
  • Vol. 1, Issue 4, 046003 (2019)
Evgenii Narimanov*
Author Affiliations
  • Purdue University, School of Electrical and Computer Engineering, Birck Nanotechnology Center, West Lafayette, Indiana, United States
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    Abstract

    We show that dielectric waveguides formed by materials with strong optical anisotropy support electromagnetic waves that combine the properties of propagating and evanescent fields. These “ghost waves” are created in tangent bifurcations that “annihilate” pairs of positive- and negative-index modes and represent the optical analogue of the “ghost orbits” in the quantum theory of nonintegrable dynamical systems. Ghost waves can be resonantly coupled to the incident evanescent field, which then grows exponentially through the anisotropic media—as in the case of negative index materials. As ghost waves are supported by transparent dielectric media, the proposed approach to electromagnetic field enhancement is free from the “curse” of material loss that is inherent to conventional negative index composites.

    1 Introduction

    Recent development of negative index metamaterials, where the subwavelength structure of the composite unit cell allows simultaneously negative electric and magnetic responses,1,2 gave rise to the experimental demonstration of such unusual phenomena as negative refraction and backwards wave propagation,3 electromagnetic cloaking,4 and subwavelength focusing.5 Particularly striking is the behavior of the evanescent waves that may show, instead of the expected decay, exponential growth through the negative index medium,2 which offers the potential to revolutionize near-field optics.6 However, this effect is only present when the metamaterial unit cell size is much smaller than the wavelength in the medium.7 As a result, while there are many different realizations of the negative index media—from photonic crystals8 to coupled Mie resonators9 to plasmonic composites10—it is only the latter class that supports this exponential enhancement of evanescent field.

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    Evgenii Narimanov. Ghost resonance in anisotropic materials: negative refractive index and evanescent field enhancement in lossless media[J]. Advanced Photonics, 2019, 1(4): 046003
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    Category: Research Articles
    Received: May. 31, 2019
    Accepted: Jul. 25, 2019
    Posted: Jul. 26, 2019
    Published Online: Aug. 26, 2019
    The Author Email: Narimanov Evgenii (evgenii@purdue.edu)