Concatenation of surface plasmon resonance sensors in a single optical fiber using tilted fiber Bragg gratings.

An inline multichannel surface plasmon resonance (SPR) sensor scheme excited with tilted fiber Bragg gratings (TFBG) in a chromium- and gold-coated fiber is demonstrated. The channels have different operating wavelengths, different TFBG tilt angles, and hence different refractive index operating ranges. The polarization state of each channel based on the TFBG orientation can be used to switch each SPR sensor on or off as required. This system provides an operating range of 1.40-1.44 RIU and a sensitivity of around 500  nm/RIU. The multiplexing in a single optical fiber of a number of TFBG-SPR sensors is demonstrated for the first time.