Anomalous photon phenomena in electromagnetic crystal systems

Abstract

In 2000, a composite material was fabricated in the gigahertz range that appeared to exhibit simultaneously negative values of permittivity and permeability. Such substances were known as "left-handed materials," and had been predicted to enable a variety of anomalous electromagnetic effects. Intense interests have developed in these materials after microwave negative refraction was experimentally observed in 2001. During the same period, a series of experiments was carried out reporting remark- able optical refraction phenomena in periodically modulated dielectric structures. A super-sensitive dependence on incidence parameters called "the superprism effect" was observed and interpreted using the anomalous group velocities in these structures. Negative refractive indices were also demonstrated and explained in terms of the backward-wave effects. Through theoretical and computational means, this research studies anomalous light phenomena in electromagnetic crystals. First, negative refraction of light is shown to be possible inside two-dimensional structures without requiring the backward- wave condition. The analysis is then extended to three-dimensional systems to predict a crystal enabling negative refraction for all incident directions. Second, transmission of evanescent waves through electromagnetic-crystal slabs is studied, and a general result is established linking bound slab resonance states to an amplification effect of evanescent waves.

(cont.) This theory is then combined with negative refraction to study the Veselago-Pendry superlensing effect, and a subwavelength focusing effect beating the classical diffraction limit is found. Third, it is proposed that the superprism effect may occur based purely on phase velocities. This effect can produce a magnitude of dispersion similar to that based on group velocities, making beam-steering possible in free space. Fourth, the analysis of light propagation is applied to the radiation from charged particles traveling through electromagnetic crystals. It is found that when coupled with Smith-Purcell radiation, Cherenkov radiation can occur with a reversed direction of propagation or a reversed radiation cone. Fifth, a model is constructed to simulate the thermal radiation from photonic crystals directly. Electromagnetic crystals are found to bring significant enhancement to the emissivity, with potential applications in thermal photovoltaic and incandescent lighting sources.