OPTICAL AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To improve excitation efficiency and to shorten an EDF for an L band. SOLUTION: Exciting light outputted by an exciting light source 24 is made incident on the EDF 20 through a WDM optical coupler 22 and excites the EDF 20. C band light before amplification is made incident on the EDF 20 from an input/output port 12 through the ports A and B of an optical circulator 18, optically amplified there and outputted from an output port 14 to the outside. The EDF 20 not only amplifies a C band by 0.98 μm exciting light but also generates the ASE light of a 1.55 μm band. Components to the port B of the optical circulator 18 within the 0.98 μm exciting light not fully absorbed in the EDF 20 and the ASE light generated in the EDF 20 are made incident on the port B of the optical circulator 18 and supplied from the port C to the EDF 16. L band light inputted from the outside to an input port 10 is made incident on the EDF 16 and optically amplified there. The optically amplified L band light is transferred through the ports C and A of the optical circulator 18 to the input/output port 12.