Long-distance simultaneous measurement of strain and temperature based on a fiber Raman laser with a single fiber Bragg grating embedded on a quartz plate

We propose and experimentally demonstrate long-distance remote simultaneous measurement of strain and temperature based on a Raman fiber laser with a single fiber Bragg grating embedded on a quartz plate. A Raman fiber laser output with a high extinction ratio of more than similar to 50 dB is achieved by the fiber grating cavity. In the sensing probe, half of the fiber Bragg grating is fixed steadily on the quartz plate to respond to temperature only, while the other half of the grating is free to respond to both temperature and strain. Based on the proposed scheme, lasing wavelength shift and separation occur with temperature and strain change, respectively. Efficient simultaneous measurement of strain and temperature for long-distance sensing applications of more than 50 km is readily obtained. (c) 2005 Optical Society of America.