Fabrication of a metal clad planar polymer waveguide based sensor for detection of low-refractive-index-contrast of liquid

A four layer polymer film based planar waveguide having a metallic clad is fabricated and analysed. The fabricated waveguide is validated for detection of small variation in the refractive index of aqueous media solution. It is observed that with increase of refractive index of aqueous media solution, the mode coupling angle of incident light increases. As the thickness of polymer film is increased from 810 nm to 1650 nm, this mode coupling angle is shifted toward higher angle of incidence. The angular interrogation of our fabricated waveguide shows that the maximum obtained sensitivity is 30 deg/RIU for 810 nm polymer film waveguide. Also, our analysis shows that the obtained experimental results are in good agreement with theoretical results.