Research On Novel Sensors Based On Plastic Optical Fiber

With the rapid development of modern electronics and biotechnology, optical fiber biosensor technology has formed an independent high-tech field. In comparison with traditional silicon fibers, plastic optical fibers (POF) have a variety of merits, such as big core diameter, high tenacity, low price, making simple, easy maintenance, high reliability etc. Thus, POF based sensors attract extensive interests of researchers. Wherein, POF based refractive index sensors have promising application prospect in microbiological testing, blood analysis, DNA analysis, toxic gas detection and other fields.This dissertation introduces the basic principles of common plastic fiber optic sensors and conventional surface plasma resonance (SPR) sensors. Depth analysis of the feasibility and superiority of POF for refractive index sensors are also presented during this work.Afterwards, several types of sensors structures are illustrated for refractive index sensing, including tapered POF, D-type POF and microporous POF. We constructed these sensing structures by fiber tapering technology, side polishing technology and mechanical drilling technology respectively.In the next section, we demonstrated superiority of graphene in refractive index sensing area. Utilizing the fact that graphene can replace the traditional metals to produce SPR as well as with the advantages of large surface volume ratio and good biocompatibility, we designed graphene-based fiber optic SPR sensor for refractive index detection. Moreover, details concerning SPR in graphene was simulated and analyzed by using the finite element method.Finally, we produced a bi-layer metal grating by laser interference lithography and then deposited it on the surface of the POF to construct a novel SPR sensor. It combines the fiber waveguide coupling and grating coupling to greatly increase the SPR excitation efficiency, which is expected to be excellent scheme for refractive index sensing.