Three-Dimensional Numerical Investigation of an Improved Surface Plasmon Resonance Waveguide Sensor

A light-guiding structure is investigated to improve the performance of a surface plasmon resonance waveguide sensor using the three-dimensional beam-propagation method. The absorption strength at the resonance wavelength is examined in terms of the core width. Calculations show that a waveguide with a wide core supporting higher order modes leads to strong absorption comparable to the two-dimensional model. Besides, embedding the core in a substrate is quite effective in obtaining a sharp dip in the wavelength response, i.e., a full-width at half-minimum is reduced from similar or equal to 11 to similar or equal to 5 nm, when the core is embedded by 0.3 mu m. This contributes to improved measurement precision.