Performance prospects for distributed measurement of Raman gain characteristics in optical fibers

A new technique has already been proposed by the authors for measuring Raman gain characteristics in single-mode optical fibers. The advantage of this technique is that it enables the evaluation of the longitudinal distribution of the Raman gain efficiency in concatenated fibers. With such distributed measurements, it is important to investigate the measurable length, which is determined by the signal-to-noise ratio (SNR) of the detected signal. In this paper, the maximum measurable length available with the previous technique was clarified based on both theoretical and experimental investigation. The SNR of the detected signal has been calculated theoretically, and it has been found that calculated and experimental results were in good agreement. Based on the SNR calculation, the measurable lengths available with this technique for various spatial resolutions and signal wavelengths are discussed.