Recent developments in the application of optical frequency domain reflectometry to distributed Bragg grating sensing

This paper presents recent developments in the use of optical frequency domain reflectometry (OFDR) to measure engineering parameters at thousands of locations along optical sensing fibers where weakly reflecting Bragg gratings have been photoetched. Application of the sensing fibers outside of the development lab has revealed several areas for improvement. Some of the problems encountered include polarization fading, non-linear laser tuning, and sensor calibration. This paper considers the use of polarization diversity detection and monitoring of the laser tuning characteristics to provide a more robust OFDR system for both sensor calibration and measurement. Possible modifications to the system are reported along with calibration measurements for quantifying the effects of polarization fading in the sensing fiber.