Dispersion Behavior of Gold-Nanocoated Dielectric Optical Fibers

P K Choudhury

doi:10.1155/2012/214614

Abstract

Using a fairly rigorous approach, gold-nanocoated dielectric optical fibers are treated to evaluate the propagation characteristics corresponding to the transverse electric (TE) and hybrid EH modes, as supported by the guides with small and large dimensions. Situations with varying nanocoating thickness are considered for two different operating wavelengths. The results demonstrate a profound effect of the gold nanocoating on the propagation-related features—the number of existing modes decreases with increasing nanolayer thickness. Furthermore, the gold nanolayer also has effects on the modal propagation constants, which become more prominent with the increase in the order of modes. It has been found that, in fiber with smaller dimension, the EH11mode hardly exhibits any effect due to the variation in existing nanolayer coating corresponding to 850 nm wavelength. Almost similar situations are observed for the TE01mode in large core fiber operating at 1550 nm wavelength.

Highlights

Substantial amount of research on optical waveguides with varieties of new forms of cross-sectional geometries and/or composite materials appeared in the literature [1–10]
Investigation reveals that the gold-nanocoating on dielectric optical fibers has the effect in the form of reducing the number of modes propagating in the fiber
We studied the cases of transverse electric (TE) and EH modes

Summary

Introduction

Substantial amount of research on optical waveguides with varieties of new forms of cross-sectional geometries and/or composite materials appeared in the literature [1–10]. The knowledge of modal behavior of gold-nanocoated optical fibers has been the vital issue to secure their usefulness in sensing, in medical diagnostics This essentially needs a thorough investigation of these fibers in terms of the sustained modes and their propagation constants. The present paper is aimed to investigate the effect of the gold-nanolayer thickness on the modal behavior of the guide, which provides the dispersion characteristics of the structure In this stream, a rigorous analytical treatment is presented for gold-nanocoated fibers of small and large dimensions under the aforesaid assumptions in respect of fields, and the effect of the gold-nanolayer is visualized through the computations of the normalized propagation constants of the modes sustained in the nanocoated fiber. Apart from the dispersion behavior, further work in the direction is in progress and will be taken up in future communications

Analytical Treatment

Results and Discussion

Conclusion