hao_photon_tunn - Unusual Photon Tunneling Caused by...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Unusual Photon Tunneling Caused by Negative Refraction Qing Hao Department of Mechanical Engineering Massachusetts Institute of Technology Abstract In recent years, tremendous efforts have been devoted to a class of novel metamaterials, left-handed materials (LHMs), which reverse the behavior of many fundamental electromagnetic properties associated with materials. In this investigation, we briefly discuss the application of LHMs in enhancing photon tunneling, which is used in thermophotovoltaic devices and scanning photon-tunneling microscopy. 1. Introduction As one of the most fundamental phenomena in optics, refraction has been studied for a long time. In the nature, all known materials exhibit positive refractive indices. When a light beam crosses the interface between two positive index media (PIM), it will be bent positively, i.e., on the opposite side of the normal to the interface. Furthermore, the Snell’s law dictates that 11 2 2 sin sin nn θ = , where 1 is the angle subtended between the incident ray and the normal, 2 is the included angle between the refracted ray and the normal, n 1 and n 2 are the refractive indices of media 1 and 2, respectively. Regarded as a common sense by many people, the above knowledge was challenged after the discovery of negative index media (NIM). In 1968, Soviet physicist Victor Veselago first hypothesized the existence of such materials with simultaneous negative permittivity ε and permeability µ , resulting in an effective negative index of refraction, n µε = [1]. Opposite to PIM, the triplet set of vectors E JG , H JJG , k G in NIM is left- handed, and thus they are also called left-handed materials (LHMs). When a ray of light passes the PIM-NIM interface, it will be bent negatively according to the Snell’s law. Due to the negative , , and n values, other fundamental phenomena such as the Doppler effect, Cerenkov radiation, anomalous refraction, and radiation pressure will also be reversed [2, 3]. Although little attention was paid to LHMs for almost thirty years, it has become a frequently mentioned topic recently since the practical realization of LH materials with split ring resonators (SRRs) and thin-wire structures were demonstrated [3, 4]. The first experimental realization based on microwave scattering was accomplished in 2001 [5]. Although divergent views were held on the explanation of the experimental data and its theoretical foundation was also questioned [6, 7], negative refraction has recently been reconfirmed in both experiments and theories [8-12]. For applications, research is actively conducted on a perfect lens [2] and unusual photon tunneling phenomena [13]. In this paper, we investigate the possibilities of using LHMs to enhance the photon tunneling through a vacuum gap. Our discussion will focus on thermophotovoltaic devices and scanning photon-tunneling microscopy. The paper is divided into three sections. The first section briefly introduces the idea of using LHMs to amplify evanescent waves in a perfect lens. The second section demonstrates this idea based on
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 calculations employing a transfer matrix method. Finally, future work in this area is
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/27/2012 for the course MECHANICAL 2.57 taught by Professor Gangchen during the Fall '04 term at MIT.

Page1 / 11

hao_photon_tunn - Unusual Photon Tunneling Caused by...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online