Experimental observation of surface plasmon resonance in a gold-coated multimode fiber

We observed for the first time evidence of the surface plasmon resonance(SPR) effect within the light distribution irradiated from a gold-coated multimode fiber immersed in a wet environment. Experimental measurements conducted with NaCl sample solutions allowed demonstrating the application of the technique in optical sensing whereby modifications in the shape of the irradiated intensity pattern are linearly correlated with changes in solute concentration. Measurement results indicate that this detection technique provides at least a 10-fold sensitivity enhancement relative to that achieved by a previously reported SPR-based fiber sensor.