FUSED OPTICAL FIBER RAMAN FREQUENCY SHIFTER AND FULLY DISTRIBUTED OPTICAL FIBER SENSOR FOR RAMAN AMPLIFIER

摘要

A fused optical fiber Raman frequency shifter and a fully distributed optical fiber sensor for a Raman amplifier. A laser light emitted by an optical fiber pulsed laser device (11) is frequency-shifted by 13.2 THz via the optical fiber Raman frequency shifter to generate a 1660 nm wave band broad spectrum Raman laser light that serves as a broad spectrum light source for the fully distributed fiber optical sensor and is emitted into a sensor optical fiber (17). Deformation and breakage of an optical fiber are detected by utilizing the principle that the reverse Rayleigh scattered light intensity of the sensor optical fiber (17) is modulated by optical fiber strain. An anti-Stokes Raman scattered light of 1550 nm wave frequency generated in the sensor optical fiber (17) is amplified via the optical fiber Raman amplifier. By deducting the effect of strain from the intensity ratio between the anti-Stokes Raman scattered light and the Rayleigh scattered light, temperature information of each optical fiber section is acquired, thus allowing detections of strain and temperature to be free of cross effects. The fully distributed optical fiber sensor utilizes optical time-domain reflectometry to position a detection point on the sensor optical fiber, is applicable in monitoring petrochemical pipelines, tunnels, large-scale civil engineering projects that are of an ultra-long range of within 100 kilometers and in disaster prediction monitoring.