Spectral interferomeric methods utilizing the interference of polarization modes in a highly birefringent fiber to measure temperature are analyzed experimentally and theoretically. First, we consider an experimental setup comprising a white-light source, a polarizer, a sensing birefringent fiber, an analyzer and a spectrometer. Temperature sensing by this method is based on the wavelength interrogation, that is the position of a chosen spectral interference fringe in a channeled spectrum is measured as a function of temperature. Employing the setup, we carried out temperature sensing in the range from 300 to 370 K when a part of the sensing fiber is exposed to temperature changes. A wavelength shift of a selected spectral interference fringe is measured and the temperature sensitivity reaches −0.11 nm/K. Second, we consider a setup with another interferometer (represented by a polarizer, a birefringent quartz crystal and an analyzer) to increase the sensitivity of the temperature sensing. In this setup, the resultant channeled spectrum is with envelope which shifts with temperature. We analyze the new sensor theoretically and show that temperature sensing is once again possible by using the wavelength interrogation and the temperature sensitivity to be reached is 0.68 nm/K.

Date Published: 5 May 2015
PDF: 8 pages
Proc. SPIE 9506, Optical Sensors 2015, 95061I (5 May 2015); doi: 10.1117/12.2182148

Published in SPIE Proceedings Vol. 9506:
Optical Sensors 2015
Francesco Baldini; Jiri Homola; Robert A. Lieberman, Editor(s)