Ultrahigh Sensitivity Plasmonic Refractive-Index Sensor for Aqueous Environment

We propose a short-length ultra-high sensitivity plasmonic-integrated optic-refractive-index sensor for aqueous medium. The sensor is based on hybrid coupling between the symmetric and anti-symmetric modes supported by the composite structure consisting of dielectric waveguide and the thin metallic plasmonic waveguide. Periodic coupling between the symmetric and anti-symmetric hybrid modes takes place, and varies with the length of the sensor. The attained numerical results show that for a properly optimized metal and buffer layer thicknesses, a sensitivity of 2 × 10
⁵
dB/RIU and resolution of 7.35 × 10
^-8
RIU can be achieved for aqueous environment, which to our knowledge, are the highest obtained so far.