Surface plasmon resonance sensor based on the Tilted Fiber Bragg Grating

This thesis proposed a new Surface Plasmon Resonance (SPR) fiber-based sensor. The sensor was realized in an un-modified standard single mode optical fiber with a Tilted Fiber Bragg Grating (TFBG) written in its core and a gold coating deposited on the surface of the fiber. TFBG is a photo-induced variation of the refractive index of the fiber's core, which enables coupling of the forward propagating core mode to the back-propagating core mode and a set of back-propagating cladding modes. SPR was excited on the surface of the gold-coated fiber through an interaction of evanescent fields of these cladding modes with the metal coating. If the wave vector of one of the cladding modes matches the wave vector of the surface plasmon wave, which can exist on the metal's surface, the plasmon wave is excited on the outer metal's surface.;The focus of this research was to determine if the gold-coated TFBG could be used to excite SPR. Simple calculations employing theory developed for TFBG and prism-based SPR configuration showed that SPR could be excited in the single mode fiber with TFBG without a need to reduce the cladding diameter. These calculations were used to predict an operating range for the proposed sensor and its sensitivity. Experiments proved that it was possible to excite SPR using the proposed sensor configuration. The sensitivity obtained for the sensor varied from 420.5 nm/refractive index unit (r.i.u.) to 539 nm/r.i.u. depending on the metal coating thickness, which is very close to the predicted sensitivity that is considered to be high among other SPR fiber-based sensors.