Coupled fiber-optic, evanescent-wave biosensors are improved through the
use of configurations which detect changes in polarization for enhanced
sensitivity. The inventive approach forms the necked-down region by
heating and pulling the fibers without twisting them. As such, when
polarized light is introduced, including randomly polarized light, the
outputs will exhibit a split based upon polarization orientation as well.
One or more bindings partners are then attached to the necked-down region
and within the evanescent field for very specific and direct detection of
minute concentrations of an analyte of interest. The invention is
applicable to any type of organic/inorganic material, so long as the
interaction of one component causes a change in any optical property
detectable by the apparatus. The biomolecule may be linked to the surface
of the fusion joint by means of a spacer molecule. Polarizing beam
splitters are employed to detect the based upon polarization orientation.
