Investigation of the self-imaging position of a singlemode-multimode-singlemode optical fiber structure

In this paper, a theoretical and experimental investigation of the multimode interference induced self-imaging phenomenon in a singlemode-multimode-singlemode (SMS) fiber structure is described. The simulated transmission spectra based on guided modal propagation analysis and beam propagation method are presented and compared with experimental obtained results. The temperature dependence of the self-imaging position of the SMS fiber structure is also investigated. These investigations provide excellent opportunities for multiple future applications including telecommunications and sensing

A temperature compensated optical fibre bending sensor for physiological measurement

peer-reviewedThe light attenuation measurement of a plastic optical fibre sensor based on a referenced intensity modulation technique with respect to different input voltage level and room temperature has been investigated. The results show that light attenuation at the sensor output and reference output are dependent on the source (LED) drive current and temperature, but the output ratio is small and tolerable for this application. This is significant for bending monitoring applications using optical fibre sensor based on intensity modulation, providing a more reliable technique based on power and temperature compensation.PUBLISHEDpeer-reviewe

The thermal properties of an SF6 circuit breaker arc during the current zero period

High speed photographic and time and space resolved spectroscopic investigations have been undertaken to quantify the processes governing arc thermal reignition phenomena. A fixed nozzle and electrode geometry was used with SF6 as the host gas. A sonic flow of gas at the nozzle throat was sustained using an upstream vessel pressure of 7.8 psig. A 35.5mF capacitor bank was used to supply electrical energy for reduced and full power arcing tests using different circuit configurations. Sophisticated optical diagnostic instrumentation has enabled photographic and spectroscopic investigations with high time and space resolution to be made during the current zero period of both the full and reduced power arcing cases. The results of above experimental investigations are of value in determining the thermal structure and the processes governing thermal reignition of the circuit breaker arc of the present investigation. In particular, temperature profiles derived from the above investigations have been used to quantify the important terms of the dynamic current zero energy balance. Experimental investigations have thus been performed during the critical current zero period of a full power circuit breaker arc. The significance of these results has been realised in evaluating the current zero temperature profiles and subsequently the energy conservation equation terms for severe circuit breaking condition