Abstract
A refractive index sensor based on a bent in-line Mach-Zehnder interferometer is investigated via numerical analysis through the beam propagation method. Comparative results are presented for the conventional not bent sensor and for the cases in which this sensor is bent at certain radii of curvature. The results showed poor sensitivity for the not bent sensor presenting a wavelength shift similar to 75 nm/RIU within the refractive index range of 1.33 to 1.41 and 55 nm/RIU near the refractive index value of 1.41. In contrast, when the sensor was bent its sensitivity was greatly increased presenting the best response at a radius of curvature of 12 mm achieving similar to 1025 nm/RIU for values of refractive index from 1.33 to 1.41 and similar to 2000 nm/RIU near the refractive index value of 1.41.

Abstract
This work presents numerical results related to an in-line Mach-Zehnder interferometer used as a refractive index sensor. The in-line Mach-Zehnder is based on abrupt tapers in standard single mode optical fiber. Numerical simulations were carried out using commercial software based on Beam Propagation Method in order to analyze the sensitivity response in terms of wavelength shift when this sensor is bent at certain radii of curvature. We realized that application of bending in the In-line Mach-Zehnder interferometer enhanced considerably the sensitivity of this sensor to the external refractive index. The best result was achieved for a radius of curvature of 10 mm (similar to 500 nm/RIU for the refractive index range of 1.33 to 1.41) improving the sensitivity about eight times in comparison with the case with no bent.

Abstract

Abstract
The work presented here describes the development and characterization of intensity fiber optic sensor integrated in a specifically designed piece of garment to measure elbow flexion. The sensing head is based on macrobending incorporated in the garment, and the increase of curvature number was studied in order to investigate which scheme provided a good result in terms of sensitivity and repeatability. Results showed the configuration that assured a higher sensitivity (0.644 dBm/deg) and better repeatability was the one with four loops. Ultimately, this sensor can be used for rehabilitation purposes to monitor human joint angles, namely, elbow flexion on stroke survivors while performing the reach functional task, which is the most common upper-limb human gesture. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)

Abstract
A triangular nanowire is fabricated by tapering a suspended-core fiber and reducing the core size below one micrometer. The triangular nanowire has a high birefringence with an order of magnitude of 10-3 and when introduced in a fiber loop mirror presents a sinusoidal interference pattern generated by the fast and slow modes of the nanowire. The suspended nanowires were characterized in temperature and strain and enhanced sensitivities were found for both parameters when compared with untapered structures.

Abstract
Triangular nanowires that present a high birefringence and a very strong confinement were fabricated by tapering suspended-core fibers (SCFs) down to core diameters below 1000 nm. Each nanowire presented a high birefringence with an order of magnitude of 10(-3). As the spectra of the SCF tapers inserted in fiber loop mirrors can be used to generate a sinusoidal interference pattern from the two main modes (fast and slow axis), a nanowire was employed as a sensing element in a Sagnac interferometer for measuring temperature. Temperature sensitivity was determined to be -56.2 pm/K using a triangular nanowire of 810 nm in-circle diameter when compared with that of a conventional untapered SCF whose temperature sensitivity is -2.1 pm/K. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)