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
A new interrogation method based on Fibre Bragg Gratings (FBG) for Surface Plamon Resonance (SPR) sensors in the region of refractive indices of aqueous solutions is described. Two FBGs are selected with their Bragg wavelengths at opposite sides of the plasmon resonance peak. The response of the system can be made independent of the fluctuations of the optical power source, and the linearity and the sensitivity of the sensor are improved. The use of the spectral selectivity of gratings for the interrogation of SPR sensors in different configurations is also promising in terms of multiplexing, temperature referencing or multiparameter detection. © 2009 SPIE.

Abstract
An optical fiber sensor for the measurement of oxygen in gaseous environments, which is based on the quenching of the fluorescence of a ruthenium complex, is presented. The sensing chemistry is immobilized in a sol-gel based solid matrix that is coated on a tapered optical fiber probe. Oxygen measurement is performed both by phase and fluorescence intensity spectroscopy. Experimental results show that the fluorescence intensity and the lifetime depend both on oxygen and temperature. A scheme for simultaneous determination of the temperature and the oxygen concentration is proposed. Temperature measurement is performed using the excitation radiation and an absorption long pass filter. Preliminary results are presented which show a temperature measurement independent of oxygen and of optical power level.

Abstract
A bulk interferometric configuration for electrical current remote sensing in high voltage environments based on the Faraday effect is described. The combination of Sagnac's reciprocal properties with a Mach-Zehnder processing interferometer in the same sensing head is used to implement serrodyne processing for current sensing. A theoretical analysis based on the Jones matrix is presented. Experimental results that validate the exploited concept are obtained, showing linearity up to 1800 A(rms) and waveform. reproduction at 50 Hz. The possibility of using the proposed interferometric concept to simultaneously fulfil the requirements associated with metering and relaying applications is also addressed.

Abstract
Optical tweezers based on metallic-coated tapered optical fibers with an aperture at the apex are fabricated and their sensing ability is tested. Preliminary results show robustness in differentiating between a trapped and no trapped state. © 2021 The Author(s).

Abstract
Fast and precise identification of minerals in geological samples is of paramount importance for the study of rock constituents and for technological applications in the context of mining. However, analyzing samples based only on the extrinsic properties of the minerals such as color can often be insufficient, making additional analysis crucial to improve the accuracy of the methods. In this context, Laser-induced breakdown spectroscopy mapping is an interesting technique to perform the study of the distribution of the chemical elements in sample surfaces, thus allowing deeper insights to help the process of mineral identification. In this work, we present the development and deployment of a processing pipeline and algorithm to identify spatial regions of the same mineralogical composition through chemical information in a fast and automatic way. Furthermore, by providing the necessary labels to the results on a training sample, we can turn this unsupervised methodology into a classifier that can be used to generalize and classify minerals in similar but unseen samples. The results obtained show good accuracy in reproducing the expected mineral regions and extend the interpretability of previous unsupervised methods with a visualization tool for cluster assignment, thus paving for future applications in contexts requiring high-throughput mineral identification systems, such as mining.