In-line fiber-optic sensors based on the excitation of surface plasma modes in metal-coated tapered fibers

Metal-coated tapered fibers are reported as refractive index sensors based on the resonant excitation of surface plasma modes supported by the metal c oating. The devices are easy to fabricate and constitute an alternative to metal-coated side-polished fibers and to other sensors made up of bulk comp onents. We report the fabrication and power transmission properties of quas i-circular devices and asymmetric devices. Both sets of devices can be oper ated as wavelength output sensors, as well as amplitude output sensors. The transmittance of quasicircular devices is polarization independent and it changes more than 30 dB as a function of external refractive index. (C) 200 1 Elsevier Science B.V. All rights reserved.