Abstract
It is reported a new dynamic electrical interrogation technique based on the modulation of two Bragg gratings structures located in the readout unit that permits to attenuate the effect of the 1/f noise of the electronics in the resolution of the LPG-based curvature sensors. The new concept is tested to detect large variations of curvature being achieved a resolution of 6.56 × 10-3 meters.

Abstract
Fiber Bragg Gratings (FBG) are widely used in various fields, including optical fiber sensors. In this work, the temperature and strain response of C-band FBG in pure silica four-leaf clover shaped suspended-core fibers was analyzed. These FBGs were fabricated by femtosecond laser exposure, which enabled the refractive index modulation of the pure-silica-core of the fibers. We compared the Bragg wavelength variation with strain and temperature for two different suspended-core fibers (256b2 and 256b5). The 256b2 fiber has a core diameter of 4,9 µm and a hollow hole inside the core with 1,4 µm; the 256b5 fiber has a solid silica core with a 7,2 µm diameter. For strain and temperature characterization, the sensing head was attached to a translation stage with a resolution of 1 µm and was placed in a tubular oven, which permits a temperature reading to be set with an error smaller than 0,1 °C. Both have shown the same sensitivity to strain (1,2 pm/µe) but different sensitivity to temperature variation (8,4 pm/°C and 10 pm/°C respectively). The relative difference between the thermal coefficients of the two selected Bragg signatures is 16%. The results obtained indicate that these gratings can be used in optical fiber sensing, for example in the context of the important problem of simultaneous strain and temperature measurement. © 2009 SPIE.

Abstract
An ultra-narrow transmission filtering scheme that combines the response of a phase-shift fiber Bragg grating and a broadband rejection micro-optical filter is proposed. The full implementation process is disclosed starting from the simulated spectral responses, grating fabrication and final assembling and test. This scheme intends to be an alternative and feasible engineering solution for one-end optical filtering interface for signal processing and analysis. © 2009 SPIE.

Abstract
In this work, an LPG-based Mach-Zehnder modal interferometer with a tapered fiber section between the two LPGs is studied as a sensing structure for measuring environmental refractive index. To interrogate this sensing device, coherence addressing and pseudo-heterodyne processing were used. A fiber taper was made between the two LPGs to improve and tailor the sensitivity of the sensor. Experimental results show that the sensitivity to external refractive index increases with the length of the taper and that the sensitivity enhancement is stronger for lower order cladding modes. © 2009 SPIE.

Abstract
In this work, interferometric sensors based on antiresonance reflecting waveguide (ARROW) fibers were developed and their performances were characterized for measurement of physical parameters, particularly strain and temperature. Two types of ARROW fibers were considered and signal demodulation was achieved using the white light interferometric technique. Application issues of sensing heads based on these fibers are also addressed. © 2009 SPIE.

Abstract
A novel miniature fiber Bragg grating (FBG) based temperature probe is presented. The sensor design integrates a ushape lossless taper thus offering the advantages of a terminal temperature probe while enabling effective serial multiplexing. We report on the experimental validation of the temperature probe design demonstrating lossless operation and effective elimination of strain cross-sensitivity. © 2009 SPIE.