Simulation of Single Mode Nanowires for Ambient Refractive Index Sensing

Low-loss optical wave guiding along a single-mode silica nanowire leaves a large amount of the guided field outside the wire as evanescent wave that is suitable for sensing element. Based on theoretical modeling, we propose to use single mode nanowires for ambient refractive index sensing. Single mode nanowire sensor employing a wire-assembled Mach-Zehnder structure is modeled. In the sensor the phase change originates from the change of refractive index of the medium surrounding the nanowire. Phase shift of the guided mode caused by index change is obtained by solving Maxwell's equation. The result shows that optical nanowires are promising for developing miniaturized optical sensors with high sensitivity.