Abstract
A fiber optic sensing system for simultaneous measurement of displacement and temperature is presented. It is based on the use of a low finesse extrinsic Fabry-Perot cavity and a fiber Bragg grating for temperature compensation. A white light tandem interferometric technique is used to recover the signal from the low finesse cavity, providing both fringe visibility and phase measurements. These, together with the fiber grating signal, give two equations that can be used to simultaneously determine temperature and displacement. Theoretical analysis of the sensing scheme is performed. Experimental results are presented which validate theoretical predictions and also demonstrate the feasibility of this sensing system in practical applications.

Abstract

Abstract

Abstract
This paper reports a technical assessment of an all-optical 4×10 Gbps clock extraction technique in the context of fiber optic digital communication systems. The technique consists in putting a 1320 nm semiconductor laser in a self pulsating mode through injection locking to a CW source. The pulsations are triggered by a fast drive current step. The useful self pulsation region has been explored after extensive simulation providing a valuable knowledge for on-going experiments. Actual synchronization with optical data stream was observed both considering all ones and pseudo-random sequences. Phase sustaining of the clock over moderate-length sequences of zeros was noticed as the most encouraging result of this work.

Abstract
We report on the use of CHF3, C2F6, and SF6 as etch gases for deep reactive ion etch processing of germano-boro-silicate glass films prepared by flame hydrolysis deposition (FHD). The glass film under study had a composition of 83 wt % SiO2, 12 wt % GeO2, and 5 wt % B2O3. The scope of the study was to identify the benefits and drawbacks of each gas for fabrication of deep structures (>10 mu m) and to develop an etch process in each peas system. The etch rate, etch profile, and surface roughness of the FHD glass films were investigated for each gas. Etch rates and surface roughness were measured using a surface profiler and etch profiles were assessed using a scanning electron microscope. It was found that SF6 had the highest FHD glass etch rate and nichrome mask selectivity (>100:1) however, it had the lowest photoresist mask selectivity (<1:2) and highest lateral erosion. CHF3 had the lowest FHD glass etch rate but high selectivity over both nichrome (>80:1) and photoresist (>10:1) and the etch profile was found to be smooth and vertical. C2F6 had a similar etch profile to that of CHF3, but the selectivity over both mask materials was lower than in CHF3. Fused silica was used as a reference material where it was found the percentage drop in etch rate in C2F6, SF6, and CHF3 was -12%, -15%, and -37%, respectively. From the results presented here CHF3 proved to be the most versatile etch process as either photoresist or nichrome masks could be used to attain depths of 20 mu m, or more. (C) 1998 American Vacuum Society.

Abstract
Fluorescence lifetimes and scatter losses for Er3+ doped, silica waveguides formed by aerosol doping and flame hydrolysis deposition are reported. The fast decay component and out of plane scatter decreased markedly with optimisation of the deposition technique, sintering process and co-doping regime. (C) 1998 Elsevier Science B.V.