Desıgn And Implementatıon Of Brıllouın Scatterıng Based Fıber Optıc Sensor


Thesis Type: Doctorate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2018

Student: MURAT YÜCEL

Supervisor: MURAT YÜCEL

Abstract:

Fiber optic cables are widely used to detect physical and chemical quantities as well as communication systems. These changes affect properties such as phase, wavelength, and intensity of the light traveling through the fiber optic cable. Various sensing techniques have been developed for this purpose. The most important of these techniques are intensity-modulated, phase-modulated, polarization-modulated, and wavelength-modulated sensors, from which distributed fiber optic sensors stand out for their ability to detect changes occurring at each point of the fiber cable. In this thesis study, a Brillouin based, fast and high resolution detection system was experimentally analyzed. For this purpose, simulations of a Brillouin scattering based distributed sensor were performed with OPTIWAVE OPTISYSTEM 7.0 program. The experimental setup for the selection of the appropriate optical cable was created and the Brillouin frequency shift for different types of fibers was measured. The temperature was changed by forming test fiber and the change of Brillouin frequency shift was investigated. For the maximum detection length, the 1550 nm band laser signal is preferred in systems. Using pulse generator and Mach-Zehnder modulator, this signal is converted into pulsed optical signals of different widths in the system. The optical signals scattered back from the fiber are collected by a data acquation card and transferred to the computer. With the developed algorithm and interface, it is possible to monitor and record the point physical changes on the optical cable. Experimental Brillouin optical time domain analysis method was established and point weight measurement was performed on single mode fiber cable and strain calculations were made.