Abstract
A pseudoheterodyne, open-loop demodulation technique? for detecting wavelength shifts in wavelength encoded fiber Bragg grating sensors is presented, The scheme uses a processing Bragg grating that is identical to one used as a sensor, When the processing fiber grating is stretched periodically, the system of two gratings produces a carrier at this frequency with its phase modulated by the measurand signal applied to the sensing grating, The demodulation technique is intrinsically immune to fluctuation of optical power in the system and is independent of the source spectral profile characteristics. A resolution of approximate to 1 mu epsilon/root Hz for static axial strain was achieved.

Abstract
A passive all-fibre technique for fibre Bragg grating wavelength shift detection which has been discussed previously is used here for the demodulation of two Bragg sensors placed in a tree topology and addressed in time. The scheme involves a light source with a particular spectral profile that allows the direct tracking of the Bragg wavelength shifts, providing satisfactory resolution over a large dynamic range and a direct application in demultiplexing fibre sensing systems. Experimental results are presented relative to the measurement of static and dynamic strain, as well as temperature.

Abstract
A passive all-fibre technique for fibre Bragg grating wavelength shift detection previously presented is used here for the demodulation of two Bragg sensors placed in a tree topology and addressed in time. The scheme involves a light source with particular spectral profile that allows the direct tracking of the Bragg wavelength shifts, providing satisfactory resolution over a large dynamic range and direct application in demultiplexing fibre sensing systems. Experimental results are presented relative to the measurement of static and dynamic strain, as well as temperature.

Abstract
A technique for the demodulation of fiber Bragg grating (FBG) sensors based on the use of a second wavelength-matched FBG receiver to track wavelength shifts from the FBG sensor is analyzed, particularly regarding its sensitivity as determined by primary noise sources. Numerical and experimental results show that there is an optimum Bragg wavelength difference between the two FBG's that maximizes the sensitivity for this demodulation technique. (C) 1997 Optical Society of America

Abstract
A new technique is described for the extraction of the intrinsic semiconductor laser parameters from intermodulation measurements of composite second-order (CSO) and composite third-order (CTB) distortion products. The effect of the parasitics elements are eliminated, by taking the distortion measurements at constant optical modulation depth, which enables one to obtain the laser parameters on packaged laser diodes. An optimization algorithm is then described that extracts the relevant laser parameters from the distortion data. This method was applied to a commercially available packaged laser diode and very good agreement was obtained between the measured and theoretical results.

Abstract
We report the experimental observation of up-conversion in an integrated silica-on-silicon waveguide. Blue light at 455 nm and 475 nm was observed. In addition to the strong blue emission near infrared (similar to 800 nm), visible (648 nm) and UV (366 nm) lines were also detected. We investigated the excitation mechanisms by using different pumping wavelengths. (C) 1997 Elsevier Science B.V.