Planar waveguide - directional coupler biosensor

• Main Author: Kok, Chiang Liang.
• Other Authors: Goh Wang Ling
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Antennas, wave guides, microwaves, radar, radio
• Online Access: http://hdl.handle.net/10356/40301
• Institution: Nanyang Technological University

In this project, the feasibility of planar waveguide based directional coupler bio-sensors are thoroughly discussed and investigated. Firstly, the different waveguide propagation modes (TE and TM) are analysed. This allows us to find a suitable value for the propagation constant, , and the coupling constant, . Secondly, directional coupler based bio-sensors are investigated on a simple 2 x 2 design whereby there are two inputs and two outputs respectively. After which, coupled mode theory is used to derive many important coupled wave equations. This is crucial for a good understanding of the coupling between waveguides. Thirdly, coupled mode theory is extended to a larger number of adjacent coupled waveguides such as three, four and five waveguides so as to investigate the coupling between waveguides and its sensitivity for sensing applications. Lastly, the coupling (TE mode) between two, three, four and five coupled adjacent waveguides is confirmed using beam propagation simulations.