A Dual-Parameter Optical Fiber Sensor for Concurrent Strain and Temperature Measurement: Design, Fabrication, Packaging, and Calibration

Coupled sensitivity of optical fiber sensors to structural strain and temperature has been a long lasting problem for reliable measurements in environments where both parameters are varying. This problem has been a driving force for the employment of methods to compensate the effect of one parameter. In this paper, a packaged dual-parameter optical fiber Bragg grating (FBG) sensor for the simultaneous measurement of structural strain and temperature using a single FBG is presented. The sensor consists of FBGs with on-fiber silver thin films synthesized by a laser direct write method. The new sensor design, fabrication, packaging, and calibration are addressed. A customized test rig and a sensor calibration package are designed and built. The performance of the sensor for the concurrent measurement of strain and temperature is investigated by analyzing the experimental data, and the characteristic curves for the calibration of the sensor are presented.