Numerical analysis of near-infrared wave propagation properties in a coated parallel planar waveguide structure for micromachined immunosensor applications

The EM wave propagation properties of layered planar microstructural waveguides are studied for their potential use in immunosensing. Simulation results are presented on the propagation of a 1 /spl mu/m EM wave in a parallel planar waveguide. Its walls are made of Si, coated with a thin layer of SiO/sub 2/ and separated by a fluid. The propagation characteristics of even and odd TE and TM modes are analysed as a function of the coating thickness. It is shown that the propagation of TE modes exhibits a sudden shift in power flow distribution from the fluid to the coating when the coating exceeds a critical thickness, a property that may be exploited for micromachined immunosensor applications.