Pumping light generator and fiber raman amplifier

摘要

An object of the present invention is to prevent an increase of the degree of polarization of an output pumping light even if one of pumping light sources has a failure. Laser diodes (30a, 30b) are composed of FP-LDs made of InGaAsP to laser-oscillate at 1480 nm band. The outputs from the laser diodes (30a, 30b) enter a polarizing beam splitter (32) in orthogonal state of polarization and are combined there. The combined light by the polarizing beam splitter (32) enters a depolarizing element (34) and is depolarized there.