Measurement of the fiber loss spectrum using fiber Raman optical-time-domain reflectometry

A new technique for the loss spectrum measurement of a fiber has been demonstrated by using fiber Raman optical-time-domain reflectometry. A Raman laser composed of a Nd³⁺:YAG laser simultaneously oscillating at two wavelengths and a multimode fiber generates a quasi-continuum spectrum, resulting from super- imposings of sequential stimulated Raman scattering and stimulated four-photon mixings. The loss spectra of two fibers were measured and were in good agreement with those obtained by the conventional cutback method within ±0.05 dB/km.