DSpace JSPUI

Fiber-optic components have got numerous applications in modern communication networks and also have very important role to play in sensing systems. However, the high cost of these components has stifled their transferal from the laboratory to the real world applications. This thesis presents an overview of the current state of art and research in different fiber optics-based network elements, sensing systems, and their principles. A cost effective and computationally fast algorithm for FBG based component synthesis and characterization has been developed using the transfer matrix method (TMM). Moreover, using pulse spreading technique, a fiber network monitoring system, i.e., a coded optical time domain reflectometer (OTDR) has been developed and implemented experimentally. A high performance long-range (21 km), cost effective distributed temperature sensor (DTS) has been implemented with the feature of further range extendibility. New schemes of a single receiver architecture and advanced signal processing techniques have been incorporated into the developed instrument for having a better performance as compared to the conventional system. The proposed DTS development was carried out using the commercially available off-the-shelf telecommunication grade components, single-mode fiber, as well as, with the multimode fiber depending upon the specific requirements. Since the proposed instrument is compatible with the most commonly used telecom-grade fiber and components, it offers an expansion over and a resultant cost reduction from the sensor systems currently in use. The undertaken research work covered a theoretical development of the scheme, a proof of principle, simulation and experimental analysis of the performance of the system. Also, investigation into sensor design requirements and the related issues are addressed in this thesis. Besides the distributed sensor, a few of the fiber based point sensors were also investigated theoretically and experimentally. These fiber sensors have got tremendous utility in civil structures, smart structures, oil and gas pipe line, oil well, mines and in other down-hole applications. Keywords: FBG, communication applications, characterization, synthesis, Transfer matrix method (TMM), pulse coding, point sensor, OTDR, Raman DTS, Brillouin DTS, single receiver architecture, single-mode and multimode fibers, strain sensor.