Performance enhancement of long-distance simultaneous measurement of strain and temperature based on a fiber Raman laser with an etched FBG

The performance enhancement of long-distance remote simultaneous measurement of strain and temperature based on a fiber Raman laser is proposed and demonstrated by an etched fiber Bragg grating (FBG) fixed on a quartz plate. An all-FBG-based Raman fiber laser with a high extinction ratio of more than /spl sim/50 dB is clearly obtained. After reducing the cladding diameter of the FBG to enhance the strain sensitivity, its half segment is fixed firmly on a quartz plate to respond to temperature only, while the other half of the etched FBG is free to respond to both temperature and strain. The lasing wavelength shift and separation occur with the temperature and strain change, respectively. The strain sensitivity is significantly enhanced to be approximately 1.6 times higher than that of a conventional FBG. A simple and effective technique for simultaneous measurement of strain and temperature for long-distance sensing applications of more than 50 km is readily achieved.