MIOMD-XI Speakers    
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1.  Prof. G. R. C Reddy, National Institute of Technology Goa, INDIA
Late-Breaking Results: Erasure dynamics of Bragg gratings in hydrogen loaded and non hydrogen loaded fibers
Speaker Biography: G. R. C Reddy: Graduated from Osmania University with majors in mathematics, physics and chemistry. He obtained his MSc. (Technology) in Engineering Physics and PhD. (Optical Information Processing) from Faculty of Engineering and Technology, NIT (REC) Warangal. He joined as a faculty in NIT Warangal in the year 1979 and became full professor in 1995 in the Department of Physics. During 2005 to 2010 he was a director of NIT Calicut and at present he is the director of NIT Goa. He was an investigator in a number of research projects sanctioned by CSIR, MHRD, and DRDO etc. He published over 80 research papers in various National and International journals / Conference proceedings. He is a specialist in Optical Information Processing. He is a Fellow of Optical Society of India, Member of SPIE and Member of OSA.

Summary: This paper presents the experimental studies conducted on the erasure dynamics of fiber Bragg gratings inscribed in germanosilicate fibers and hydrogenated fibers by monitoring the reflected peak power with temperature. Experimental study on the thermal response of the FBGs written in non hydrogenated fibers revealed that they are thermally stable at lower temperatures only, i.e. up to about 300 °C and therefore are suitable for low temperature applications. Beyond this temperature, the reflected peak power from these gratings has decreased quickly and the gratings are permanently washed out by exposure to temperatures above 350 °C. Whereas, the experimental studies on the erasure dynamics on the third FBG i.e. with hydrogen loading reveal that they are capable of withstanding up to around 900 °C compared to the ones written in non hydrogen loaded fibers. It is further noticed that in the case of these fibers, at any given temperature, the same wavelength shift is noticed while the temperature is increasing or decreasing. Further, the response of the hydrogen loaded fibers is found to be linear and the rates of shift of wavelength values are also found exactly coinciding whether the temperature is increasing or decreasing. This proves the existence of regenerative property of hydrogen loaded fiber grating. Because of this regenerative property, anomalous effect of temperature over wavelength is not noticed. These results indicate that this grating sensor performs reliably as an ultra high temperature component in sensor applications.
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