Abstract
In this paper, two hybrid multimode/single mode fiber Fabry-Perot (FP) cavities were compared. The cavities fabricated by chemical etching are presented as high temperature and strain sensors. In order to produce this FP cavity a single mode fiber was spliced to a graded index multimode fiber with 62.5 mu m core diameter. The Fabry-Perot cavities were tested as a high temperature sensor in the range between room temperature and 700 C and as strain sensors. A reversible shift of the interferometric peaks with temperature allowed to estimate a sensitivity of 0.75 +/- 0.03 pm/degrees C and 0.98 +/- 0.04 pm/degrees C for the sensor A and B respectively. For strain measurement sensor A demonstrated a sensitivity of 1.85 +/- 0.07 pm/mu and sensor B showed a sensitivity of 3.14 +/- 0.05 pm/mu. The sensors demonstrated the feasibility of low cost fiber optic sensors for high temperature and strain.

Abstract
Recent advances in the application of semiconductor nanocrystals, or quantum dots, as biochemical sensors are reviewed. Quantum dots have unique optical properties that make them promising alternatives to traditional dyes in many luminescence based bioanalytical techniques. An overview of the more relevant progresses in the application of quantum dots as biochemical probes is addressed. Special focus will be given to configurations where the sensing dots are incorporated in solid membranes and immobilized in optical fibers or planar waveguide platforms.

Abstract
An amplitude-phase-conversion self-referencing technique for intensity-modulated photonic sensors that uses two different-wavelength fiber Bragg gratings is presented. With this technique, the system response has been demonstrated to be almost unafffected by network power variations as high as 90%, of the total power launched by the source. We prove the multiplexing capability of this type of self-referenced fiber sensor by wavelength-division multiplexing two of them in a star network. A tunable fused biconical wavelength-division multiplexer is used for sensor addressing at the detection block, providing both good isolation and low cross-talk values. (C) 2002 Optical Society of America.

Abstract
We present and numerically characterize a surface-plasmon-resonance sensor based on an H-shaped optical fiber. In our design, the two U-shaped grooves of the H-fiber are first coated with a thin gold layer and then covered by a uniform titanium dioxide layer to facilitate spectral tuning of the device. A finite element method analysis of the sensor indicates that a refractive-index resolution of up to 5.10(3) nm/RIU can be obtained. (C) 2011 Optical Society of America

Abstract
We study the measurand-induced spectral shift of the photonic bandgap edge of a hollow-core photonic crystal fiber. The physical measurands considered are strain, temperature, curvature, and twist. A noticeable sensitivity to strain, temperature, and twist is observed, with a blueshift to increase strain and twist. An increase in temperature induces a redshift. On the other hand, curvature has no observable effect on the spectral position of the photonic bandgap edge. (C) 2010 Optical Society of America

Abstract
A network for multiplexing fiber Bragg gratings (FBGs) and intensity-modulated fiber-optic sensors with no need to distinguish between the two kinds of sensor is proposed and experimentally demonstrated. Two FBG sensors and two intensity-modulated sensors are wavelength-division multiplexed; the electrical phase of the output signal is measured as a common parameter for both types of sensor. Furthermore, the intensity sensors become power referenced, and the FBG sensors are interrogated by a low-cost technique. Low cross talk is achieved by use of a tunable optical filter at the detector. (C) 2003 Optical Society of America.