Improvement of functions in synthesis and scan of the optical co-herence function and its applications to distributed photonic sensing

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The author has invented a technique, in which optical coherence function can be synthesised in arbitrary shapes. Moreover, additional technique has also been invented to scan the function by using a phase modulation on the reference lightwave in the interferometer. In this research project, this principle is applied to construct new distributed sensing systems.At first, phase-modulationg Optical Coherence Domain Refrectomatry by Synthesis of CO-herence Function, p-OCDR for short, has been proposed. In the previous OCDR method, not only synthesising but also scanning the coherence function was carried out by the lasing frequency modulation of a semiconductor lase. On the contrary, in p-OCDR the scanning is done by the phase modulation, which results in increasing the accuracy of the synthesised shape. Deterioration factors in p-OCDR were considred to found the countermeasures, then 1.2mm resolution and -100 dB sensitivity have been realized. To diagnose divices at the end of optical sub … More scriber networks in the Fiber TO The Home system, new reflectometry with high spatial resolution and long range has also been proposed. Reflectivity distribution at about 5Km far end has successfully been measured with 6cm resolution. Next, p-OCDR has been applied to measure mode coupling distribution between two polalization eigen modes in a polalization maintaining fiber, which provide a distributed pressure sensing system. An experimental system has been constructed, which has shown the resolution of 9m and the measurable range of 1Km.We have also studied a method to mauti/demultiplex sensor outputs from fiber interfero-metric sensors. Phase information from one sensor has successfully been selected from others by using Synthesis of the Coherence Function Technique. Moreover, an optical tomography system has also been proposed utilising the thechnique, in which no mechanical moving part any calculation are needed.As described above, enough research results have been accululated on this research project. Less