Abstract
A dual-core fiber in which one of the cores is doped with Germanium and the other with Phosphorus is used as an in-line Mach-Zehnder (MZ) interferometer to perform high sensitivity strain and temperature sensing. Opposite sensitivities for high and low wavelength peaks were demonstrated when strain was applied. To our knowledge this is the first time that such behavior is demonstrated using this type of in-line MZ interferometer based on a dual-core fiber. A sensitivity of (78 +/- 2) pm/mu epsilon, between 0-950 mu epsilon and (1380 +/- 20) pm/degrees C between 45 and 80 degrees C is demonstrated. It was also demonstrated that it is possible to use this configuration for simultaneous measurement of strain and temperature and a matrix equation to calculate them was given.

Abstract
A fiber loop mirror containing a section of high-birefringence suspended-core fiber is used for torsion sensing. The suspended-core fiber section has a triangular-shaped core with an in-circle diameter of approximately 1.8 mu m. Due to its small dimensions and geometric structure, it presents high birefringence and intermodal interference simultaneously. A torsion sensitivity of 59.0 pm/deg is obtained in a very large linear range of 900 deg with a resolution of 1.2 deg. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI: 10.1117/1.OE.52.2.020501]

Abstract
A new, fiber-based, cavity ring-down topology is presented which enables the application of the cavity ring-down technique to remote sensing, by the use of a large cavity ring and an optical circulator. For a proof of concept a 1.5 km ring is assembled and a taper is used as a sensing head for measuring displacement. The cavity ring-down technique is seen to hold some potential for remote sensing through its implementation on optical fibers.

Abstract
A combination of focused ion beam milling and chemical etching is proposed for the creation of Fabry-Perot cavities in microwires. Both simple cavities and cantilevers are created on 15 mu m-diameter microwires and characterized in temperature. The cantilever structure shows sensitivity to vibration and is capable of measuring frequencies in the range 1 Hz - 40 kHz.

Abstract
A review in fiber post-processing for sensing applications is presented. The review is divided in three parts. Tapers devices, chemical etching for Fabry-Perot cavities and focused ion beam (FIB) as post-processing applied in optical fibers are considered. The most recent results as sensing elements are shown. © 2014 OSA.

Abstract
Tapering single-mode-multimode-single-mode structures to enhance sensitivity is proposed and experimentally demonstrated. 50-mm-long coreless multimode fiber sections are spliced between single-mode fibers (SMFs) and tapered. They are characterized in strain, and an increase in strain sensitivity is obtained with taper diameter reduction. Sensitivities as high as -23.69 pm/mu epsilon for the 15-mu m taper are attained. Temperature sensitivities also depend on taper diameter. A combination of two different diameter tapered SMF MMF-SMF structures, with cross-sensitivity to strain and temperature, is proposed as a sensing system for the simultaneous measurement of strain and temperature with resolutions of +/-5.6 mu epsilon and +/-1.6 degrees C, respectively. A good condition number of 3.16 is achieved with this sensing structure.