Journal of Physical Chemistry & Biophysics
Open Access

Studies on high temperature sensor upto 1000ºC based on thermally regenerated fiber Bragg gratings

3^rd International Conference and Exhibition on Lasers, Optics & Photonics

September 01-03, 2015 Valencia, Spain

Om Prakash

Raja Ramanna Centre for Advanced Technology, India

Posters-Accepted Abstracts: J Phys Chem Biophys

Abstract :

This paper presents the studies on high reflectivity thermally regenerated fiber Bragg grating (FBG) in hydrogen loaded photosensitive opticalfibers. The effect of Ge and Ge-B co-doping in fused silica fibers on the reflectivity of thermally regenerated gratings and the residual reflectivity of regenerated fiber Bragg gratings at elevated temperature upto 1100�ºC, are presented. Type-I FBGs of almost similar transmission loss/reflectivity (~ 35 dB) were inscribed as the seed gratingin the core of various H2 loaded fused silica fibers having different molar doping concentrations of only Ge and B-Ge. The FBG inscription is carried out using 255 nmUV source atrepetition rate of 5.6 kHz.The seed type I FBGs were subjected to multi-step annealing process upto 1100�ºC spanning over 60 hours for studying thermal regeneration characteristics andtemperature sustainability. Two regeneration regimes were observed for FBGs written in Ge doped fiber whereas single thermal regeneration was observed for Ge-B co-doped fiber. At 1100�ºC, the residual reflectivityof 0.1% (for Ge-B co-doped fiber), 40% (for 3% Ge doping), 43% (for 10% Ge doping) and 10% (for 18% Ge doping) were obtained. The residual reflectivity is linked with the structural modification of the grating which is experimentally confirmed from the dc refractive index change during regeneration of the FBG. Structural transformation in fused silica fiber due to annealing at high temperature (1100�ºC) is also confirmed by Synchrotron X-ray diffraction measurement of un-annealed and annealed fibers.

Biography :

Email: oprakash@rrcat.gov.in