Study of light propagation in dielectric loaded surface plasmon polariton waveguides

• Main Author: Chen, Shiyi.
• Other Authors: Ang Lay Kee Ricky
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Optics, optoelectronics, photonics
• Online Access: http://hdl.handle.net/10356/17905
• Institution: Nanyang Technological University

Surface plasmon polaritons (SPPs), have become a hot research topic recently, due to their ability to confine and guide optical signals on subwavelength scales. Dielectric-loaded SPP waveguide (DLSPPW) is one type of SPP waveguides which has received particular interest since it is low cost, relative easy to be fabricated and provide better lateral confinement as well as low bend and propagation losses. In this project we have studied different DLSPPW structures for light guiding and sensing purpose. Throughout the project, we have used Lumerical FDTD Solution (a commercial software based on the Finite-Difference Time-Domain) to model the DLSPPWs as well as to calculate the performance of the proposed structures. This project is divided into three parts. The first part consists of a comprehensive investigation of the influences of geometry and material composition on the mode profile of DLSPPW. Three different shapes of dielectric ridge: triangle, rectangle and ellipse are proposed. The dimensions of the ridge are studied in order to achieve high confinement and low propagation loss. Moreover, different types of metal films as well as different dielectric materials are also taken into consideration. The second part is to study the propagation properties of DLSPPW with holes drilled inside the dielectric ridge. It is found that by filling the hole with different dielectric materials, high transmittance can be achieved only for wavelength within a certain range, which acts like a bandpass optical filter. Moreover, the resonant frequency shifts with the change of the hole dimension and the material filled inside. Looking beyond the straight line DLSPPWs, the last part of the project is the study of right angle bend with rounded corner and S shaped bend DLSPPWs. By varying geometric parameters such as the bend radius of the right angle as well as the horizontal and vertical offset of the S bend, optimum structures with minimum bending loss are both achieved for these two types of bending structures. Furthermore, based on the bends, a demultiplexer that is able to guide light to different ports depending on the operating wavelength is proposed and presented.