Long-length fiber-optic remote Raman sensors are used for distributed temperature measurements. Toward this aim, we apply optical-fiber frequency-domain reflectometry. The Raman intensity generated in single- and multimode optical fibers is theoretically investigated for sinusoidally intensity-modulated probe light. Thus, a proper sensor element and wavelength for fiber-optic Raman sensing is determined. Further, the temperature error for long sensor fibers is theoretically analyzed.
Mostafa Ahangrani Farahani and Torsten Gogolla, "Spontaneous Raman Scattering in Optical Fibers with Modulated Probe Light for Distributed Temperature Raman Remote Sensing," J. Lightwave Technol. 17, 1379- (1999)