简介 |
In an optical amplifier wherein pumping laser light and signal laser light are multiplexed and supplied as input to a fiber doped with a rare earth element, by decreasing the number of connected sections, loss due to the connection to the rare earth-doped fiber is decreased. A pair of fibers, each consisting of an undoped optical fiber (1a, 1b) fusion spliced to a rare earth-doped fiber (4a, 4b), are arranged in parallel and heated and fused with each other to form a fused jointed portion (3) which is stretched in the vicinity of the connection point (2), thereby forming the optical coupler. |