Abstract
An analytical model based on geometrical optics and multilayer transfer matrix method is applied to the surface plasmonic resonance supported by fibre taper structures in the context of optical sensing applications. Phase interrogation is considered in particular as a methodology to attain enhanced sensitivities, and the performance of the sensing heads as function of the metal clad and taper parameters is analyzed. General topics concerning the actual relevance of plasmonics are also presented, first in a global perspective and then when applied to sensing.

Abstract
A figure-of-eight based fibre laser cavity is proposed for the measurement of torsion. In one of the loops a section of photonic crystal fibre is inserted, acting both as an optical filter and the sensing head. The laser emission depends on the optical filter polarization and length. A single lasing band is achieved with a full width at half maximum of similar to 1.72 nm. The proposed sensor presents sensitivity to torsion of 7.13 pm/degree over a range of 180 degrees. This configuration can also be used to measure optical power variations. Besides, due to the properties of the optical filter this sensor presents low sensitivity to temperature.

Abstract
A vibration sensor based on a distributed Bragg reflector (DBR) is proposed. The gratings that form the cavity are written in erbium-doped fibre using the femtosecond laser technique. In this configuration, one grating of the DBR acts as a sensor whilst the other one acts as a spectral filter. The active sensor, subjected to vibration measurements, exhibits a response of up to similar to 1.5 kHz.

Abstract
With the objective to study the variation of optical properties of rat muscle during optical clearing, we have performed a set of optical measurements from that kind of tissue. The measurements performed were total transmittance, collimated transmittance, specular reflectance and total reflectance. This set of measurements is sufficient to determine diffuse reflectance and absorbance of the sample, also necessary to estimate the optical properties. All the performed measurements and calculated quantities will be used later in inverse Monte Carlo (IMC) simulations to determine the evolution of the optical properties of muscle during treatments with ethylene glycol and glucose. The results obtained with the measurements already provide some information about the optical clearing treatments applied to the muscle and translate the mechanisms of turning the tissue more transparent and sequence of regimes of optical clearing.

Abstract
A magneto-optical current sensor, based on a low birefringence SF57 glass prism, using a dual quadrature polarimetric configuration was implemented and tested aiming its application in high voltage power lines. Sensor operation is characterized and compared using distinct Super Luminescent Diodes as optical sources, with emission at 650 nm, 830 nm and 1550 nm. Calibration and resolution are obtained in the different operating conditions using a DAQ board and full digital control for signal acquisition and processing. In particular, the sensor was tested in the range from 0 to 1 kA at 50 Hz. Also, operation at different frequencies from 50 Hz to 400 Hz was compared. A robust casing was fabricated in Nylon material enabling the portability of the sensor and its application in different types of conductors. Preliminary results indicate the feasibility of using the sensor both for metering and protection applications in high-power lines with interrogation via the OPGW cable.

Abstract
A fiber optic interrogation sensor scheme based on a "figure-of-eight" configuration created from a single directional 3 x 3 fiber optic coupler is proposed. Two loops are formed in each arm and one of them contains the sensing head and the other is used as reference signal. A theoretical study based on Jones matrix analysis of this fiber loop mirror combination is reported. The optical configuration is tested as an interrogation scheme for a fiber strain sensor where the spectral response arises from the combination of the reference signal modulated by the sensor signal. The strain sensor configuration shows a phase sensitivity of 6.7 +/- 4.38 x 10(-2) mrad/mu strain by linear regression.