In this paper we present an experimental study on the surface plasmon resonance (SPR) based fiber optic sensor for the detection of hydrogen. Wavelength interrogation mode of operation has been used for sensing. The probe is fabricated by coating silver, silicon and palladium (Pd) layers over unclad core of the fiber. The fact that the presence of hydrogen in the air around the palladium changes the dielectric functions of palladium is utilized. The SPR spectra are obtained for 100% nitrogen as well as for a mixture of 4% hydrogen and 96% nitrogen. A shift in resonance wavelength is obtained. The shift initially increases with time and then saturates. The silicon layer enhances the shift in resonance wavelength.
Surface plasmon resonance based tapered fiber optic refractive index sensor incorporating an additional high index
dielectric layer between metal and sensing medium using wavelength interrogation method is analyzed. The
simulation is carried out for gold and silver metals. The simulation predicts, for a given taper ratio, the increase in
the sensitivity of the sensor with increase in the thickness of the dielectric layer. The sensitivity also increases with
the increase in the taper ratio. The advantages of additional layer of dielectric, in addition to the increase in
sensitivity, are the protection of metallic layer from oxidation and the tuning of wavelength range of operation of the