Abstract
In this work, we present a fiber Bragg grating interrogation based on high-birefringence fiber loop mirror for strain-temperature discrimination. Due to spectral response of the optical filters it is possible to determine the variation of the wavelength and the optical power of the Bragg grating sensor when subject to strain or temperature. Maximum errors of +/- 0.4 degrees C and 12 mu epsilon are reported over 80 degrees C and 2000 mu epsilon measurement ranges. (c) 2006 Wiley Periodicals, Inc.

Abstract
An optical current sensor based on a metal coated Hi-Bi fiber loop mirror is reported. This current sensor quantifies the current through the measurement of the temperature which varies accordingly with the magnitude of the electrical current. The temperature change is analyzed through the variation of the wavelength shift of a fringe minimum of a Hi-Bi fiber loop mirror. The minimum current detection was found to be approximately 10 A. (c) 2008 Wiley Periodicals, Inc.

Abstract
In the present paper, the influence of the fiber Bragg grating (FBG) length and its coating on embedded FBGs in polymers is evaluated. Different FBG lengths and coatings, uncoated and acrylate-recoated, are used. The evolution of their spectra is also followed during laminate curing on a hot-plate press. The Bragg gratings are used as optical fiber sensors, and their sensitivity and reliability are analyzed. The resulting sensor signal characteristics and the strain answers to different loading modes, i.e. tensile, flexural and through-thickness compression, are also studied.

Abstract
An optical fibre sensor for determination of acetic acid is presented. The sensing probe is based on a fibre Bragg grating (FBG) Fabry-Perot cavity, coated with a thin film of sol-gel-PVP (polyvinylpyrrolidone) composite material. The polymeric thin film renders the interferometric output sensitive to the presence of carboxylic acid species. Results show that the wavelength of the interferometric peaks changes with acetic acid concentration, enabling its quantification. Coupling the fibre probe with a serrodyne modulated readout interferometer enables pseudo-heterodyne interrogation and the detection of acetic acid with a sensitivity of 92.6 deg/% L/L and a resolution of 0.2% L/L. The results demonstrate the potential of the proposed scheme to operate as a sensitive chemical sensor platform.

Abstract
In this work, a laser sensor that uses the multipath interference produced inside a ring cavity to measure the power loss induced by a moving taper intensity sensor is described. The laser is created due to the virtual distributed mirror formed by the Rayleigh scattering produced in a dispersion compensating fibre when pumped by a Raman laser. Two laser peaks were formed, one of them is obtained by the Raman gain (1555 nm) inside the ring and the second is created by the combination of the Raman gain and the Rayleigh scattering (1565 nm). A taper sensor is used as displacement sensor and with the increases of losses the second laser peak amplitude is reduced. In the process the first peak is maintained constant and can be used as reference level.

Abstract
The strain and temperature sensing characteristics of a modal interferometer based on two Bragg fibers have been investigated. The special nature of this sensor is that the two Bragg fibers used present a different external cladding shape. It appears that the sensitivity to the sensing parameters are different for the two Bragg fibers, which makes it possible to fabricate several sensing configurations based on the combination of these two Bragg fibers for strain and temperature discrimination.