A refractometric sensor using index-sensitive mode resonance between single-mode fiber and thin film amorphous silicon waveguide

A waveguide structure consisting of a side-polished single-mode polarization maintaining (PM) fiber and amorphous silicon film on top was applied for “in situ” control of the amorphous silicon deposition process. The changes in the fiber output intensities resulting from the film thickness growing were measured. The interaction of the fiber mode and TE0 and TE1 planar waveguide (PWG) modes was investigated. The applicability of the structure as a high sensitive refractometric sensor element was demonstrated.