Abstract
Coal has been for centuries a central energy source to fulfill industrial and domestic needs. Its large scale extraction produced huge amount of debris that were piled in the neighboring of the mines, quite often going into combustion triggered by events like forest fires or lightning. When in this state it can continue for years, releasing substantial emissions of toxic and greenhouse gases with recognized impact in the environment and, more serious in the short term, in the life quality of the populations located nearby. Continuous monitoring of combustion temperature and emission levels of certain gases opens the possibility to plan corrective actions to minimize their negative impact. Optical fiber technology is wellsuited to this purpose and here it is described the main attributes of a fiber optic sensing system projected to gather data on distributed temperature and gas emission in these harsh environments.

Abstract
In this work, an all-fiber loop mirror using a four-bridge silica fiber with a double-Y-shaped suspended-core is presented for the measurement of strain and torsion. The sensing head is formed by a section of the microstructured fiber with 90 mm in length. The fiber loop sensor allowed observing a distinct interference pattern as a result of the geometry of the core fiber. Different sensitivities to strain and torsion were obtained, namely, -5.11 pm/mu e and +/- 1.34 pm/degree.

Abstract
We propose a refractive index sensor based on surface plasmon resonance (SPR) in a gold wire partially incrusted on the surface of a D-type fiber and in contact with the external medium for increased sensitivity and roughness. The sensor is studied using numerical simulations based on the finite element method (FEM) and is compared with a more conventional D-type fiber SPR where the wire is replaced with a gold film. The numerical work estimates the sensitivity and resolution for different analytic refractive indexes (RI) in the range of 1.30-1.40, for a sensor based on the wavelength interrogation method. The results indicate that the use of the gold wire provides a better sensitivity when compared with the gold film, while supporting multiple peaks in different wavelengths, each with distinct values of sensitivity and resolution.

Abstract
This paper presents a numerically investigation of the performance analysis of a conventional photonic crystal fiber (PCF) with a planar metamaterials structure for refractive index sensing, based on surface plasmon resonance (SPR), using the finite element method (FEM). We study the concentration metamaterials conformed by the aluminium oxide (Al2O3) and silver (Ag) and compared its performance with a single metal (Ag), assessing their impacts in the effective refractive index. Furthermore, we also use different types of mechanics to describe the effects of varying the structural parameters sensor on the evanescent field and the sensor performance.

Abstract
In this work two erbium doped optical fiber laser configurations for magnetic field measurement are implemented and compared. The first laser is set-up in a loop configuration and requires only a single FBG (Fiber Bragg Grating), acting as mirror. A second laser employs a simpler linear cavity configuration but requires two FBGs with spectral overlap to form the laser cavity. A bulk magnetostrictive material made of Terfenol-D is attached to the laser FBGs enabling modulation of its operation wavelength by the magnetic field. Moreover, a passive interferometer was developed to demodulate the AC magnetic field information where the corresponding demodulation algorithms were software based. Both configurations are tested and compared with the results showing different sensitivities and resolutions. Better performance was accomplished with the double FBGs linear cavity configuration with a resolution of 0.05 mTRMS in the range of 8 to 16 mTRMS. For the same range the loop configuration attained a resolution of 0.48 mT(RMS).

Abstract
A sensing configuration based on an intensity optical fibre sensor for temperature measurement is reported. Two sensing heads, with identical geometrical configuration, connected in series are implemented. Each sensing head is placed between two fibre Bragg gratings (FBGs), being able to provide a self-referenced measurement, and thus eliminate errors that may arise from undesired intensity fluctuations in the configuration. The first FBG, placed before the aluminium tube, acts as the reference FBG, while the second FBG, placed after the aluminium tube, acts as the signal FBG. It is observed that the amplitude of the signal FBG decays when temperature increases, due to the increase of the ferrules' gap and as result of the material thermal expansion. The temperature response has a behaviour that corresponds to a polynomial fit of third order. The crosstalk between the two sensing heads in series is analysed. The temperature sensitivities obtained in the intervals regions of [36, 48.5] degrees C and [64, 85] degrees C are 2.67 x 10(-3) degrees C-1 and 1.74 x 10(-4) degrees C-1, respectively. Ten sensing heads with this configuration can be multiplexed in series network topology.