Abstract
In the field of aqueous environment studies, long-period fiber gratings are very attractive for the real-time monitoring of physical parameters, such as temperature and salinity. However, due to the fiber jacket removal, these are fragile devices when applied in real conditions, where mechanical loads and contamination with algae and other organic materials must be taken into account. This work describes a refractive index sensing head that has been developed and characterized for in situ measurement of water salinity and resistance to hard conditions.

Abstract
In this work we describe the characterization of high Q optical microresonators using an all fiber based system. Silica microspheres fabricated on a fiber tip by electric arc discharge are characterized using a simple interrogation system based on an adiabatic fiber taper coupler and on the collection of scattered radiation by a multimode fiber.

Abstract
Theoretical and experimental results were presented which validated a new dual interferometric configuration with serrodyne processing for the remote sensing of electrical current. Linearity and waveform reproduction at 50 Hz were observed and a current resolution (˜22.4 ArmsHz- 1/2) was obtained. The utilization of the proposed interferometric concept to simultaneously perform metering and relaying current measurements was also addressed. © 2002 IEEE.

Abstract

Abstract
The use of semiconductor nano-particles as temperature probes in luminescence chemical sensing applications is addressed. Temperature changes the intensity, the peak wavelength and the spectral width of the quantum dots luminescent emission in a linear and reversible way. Results are presented that show the feasibility of implementing a self-referenced intensity based sensor to perform temperature measurements independent of the optical power level in the sensing system. Additionally, it is demonstrated that self-referenced temperature measurements in multiple points could be performed using reflection or transmission based optical fiber configurations.

Abstract
The suitability of semiconductor nanoparticles to provide a reference signal in luminescence based chemical sensors is addressed. A CdSe-ZnS nanocrystal, with emission peak at 520 nm is used to provide a reference signal. Measurements of oxygen concentration, which are based on the dynamic quenching of the luminescence of a Ruthenium complex, are performed. Both dye and the nanocrystal are immobilized in a sol-gel matrix and are excited by a blue LED. Results are presented showing that the ratio between the reference and the sensor signals is highly insensitive to fluctuations of the excitation optical power. Preliminary results show that nanocrystals could be used to measure temperature and provide a reference signal.