EXCITING LIGHT SOURCE DEVICE FOR RAMAN OPTICAL AMPLIFICATION, AND RAMAN OPTICAL AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To solve the problem when a semiconductor laser element for excitation is made into one, the fluctuations in a Raman amplification gain with the lapse of time due to the fluctuations in the polarization of excitation light or signal light with the lapse of time appear. SOLUTION: The excitation device 7 for Raman optical amplification for outputting the excitation light for subjecting the signal light introduced into an optical fiber to Raman optical amplification within the optical fiber comprises two light sources 71 and 72, a polarized light combiner or polarization maintaining light combiner 8 which inputs two light and synthesizes the light and outputs and an unpolarizer 9 which unpolarizes the input light and outputs the same. The light rays outputted from the two light sources are inputted to the polarized light synthesizer or polarization maintaining light synthesizer and the combined composite light is outputted. This composite light is inputted to the unpolarizer and the light decreased in the degree of polarization is outputted.