Optical waveguide chemical and biological sensor

摘要

An optical waveguide sensor particularly useful as a chemical or biological sensor is described which comprises a single mode fibre optic waveguide including a core surrounded by a cladding and having a tapered portion which tapers adiabatically inwardly to a waist of diameter typically about that of the original core, and then adiabatically outwardly by variation of the cladding whereby under operating conditions the evanescent electromagnetic field associated with the guided mode of the waveguide is externally accessible in the region of the tapered portion; an optical source, such as a laser, optically coupled to one end of the waveguide; and a detector coupled to the other end of the waveguide for detecting optical radiation modulated or coupled into the waveguide at the tapered portion. The tapered portion is preferably in the form of a loop to facilitate construction of the sensor as a probe, and includes a binder for binding a chemical or biological compound, for example, a silane for use in conjunction with a recognition entity.