Ray-tracing determination of evanescent-wave penetration depth in tapered fiber optic probes

摘要

Abstract: optic biosensor has been developed which monitors fluorescence to detect antibody/antigen binding within the evanescent wave. The sensing region is formed by removal of cladding from the core along the distal end of a step﹊ndex optical fiber and attaching the antibody. Reducing the radius by tapering the probe overcomes the mismatch in V﹏umber which arises between the declad, immersed probe, and the clad fiber. Ray tracing analysis of tapered probes and of combination taper probes demonstrates that the evanescent wave penetration depth increases along the length of the taper, creating a probe with increased excitation light available at the surface for stimulating fluorescence. !3