Abstract
Flame hydrolysis deposited (FHD) silica waveguides are very important for use in planar lightwave circuits (PLC) because of their low loss and inherent compatibility with silica optical fibers. A low damage, anisotropic reactive ion etch process for the fabrication of single and multimode waveguides in silica for planar lightwave circuit applications is presented. The etch rate of the glass results in smooth sidewalls and deep anisotropic etching. Propagation losses and polarization sensitivity arising from the etch process are discussed.

Abstract
We report what is to our knowledge the first laser operation of Nd3+-doped LiNbO3 near 900 nm. An absorbed power threshold of 26 mW was obtained when the device was pumped at 814 nm. The design of the waveguide geometry to favor laser operation at this wavelength is demonstrated. (C) 1997 Optical Society of America.

Abstract
An investigation is performed on the characteristics of the self-referencing resonant fiber optic intensity based sensor supported by a Mach-Zehnder topology. Both transmissive and reflective configurations are analyzed. Via the definition of the measurement parameter (R parameter) the linearity and sensitivity of the sensor are addressed. Theoretical and experimental results are compared. The problem of sensor design is under consideration. (C) 1996 American Institute of Physics.

Abstract
A passive all-fibre technique for Bragg wavelength shift detection is presented which can be considered as the minimum configuration for fibre grating sensing demodulation. The scheme involves a light source with a particular spectral profile that allows the direct tracking of Bragg wavelength shifts. Referencing to source power fluctuations is also provided. This simple technique shows satisfactory resolution over a large dynamic range. Experimental results are presented for temperature and strain measurements. © 1996 IOP Publishing Ltd.

Abstract
An optical sensor capable of simultaneously measuring displacement and temperature is presented. It incorporates a fiber Bragg grating temperature sensor and a low-finesse extrinsic Fabry-Perot cavity. A white light tandem interferometric technique is used to recover signal from the low finesse cavity. Signals obtained from the interferometer and the Bragg grating provide required information to simultaneously determine temperature and displacement. Experimental results are presented which demonstrate the feasibility of this sensor topology in practical applications.

Abstract
An investigation is performed of the characteristics of the self-referencing intensity based Q-type fibre optic sensor using a recirculation loop structure. Both transmissive and reflective configurations are analysed. Via the definition of the measurement parameter (the R parameter) the linearity and sensitivity of the sensor are addressed. Theoretical and experimental results are compared, considering the problem of sensor design and optimization. © 1995 Taylor & Francis Ltd.