Fiber-optic waveguide coupled surface plasmon resonance sensor.

A novel approach to give an excellent tunability and self-referencing capability was presented by applying a concept of waveguide coupled surface plasmon resonance mode to a fiber-optic sensor. The presence of dielectric waveguide sandwiched between two metal layers made it possible to precisely tune the resonance wavelength in a broad range from visible to infrared region and to generate multiple modes which may be selectively used for suitable applications. Our approach also verified the potential capability of self-referencing based on a remarkable difference in sensitivity between the plasmonic and waveguide modes excited by p- and s-polarized lights, respectively, without using an additional reference channel. Experimental measurement carried out on sucrose solutions with varying concentration demonstrated the feasibility of our approach.