Patent ID: 8837885

Claim:
An optic coupler comprising: a first optical fiber having a first core and a first cladding surrounding the first core; a second optical fiber transmitting a signal light to the first optical fiber, the second optical fiber being a few mode optical fiber having a second core and a third cladding surrounding the second core; third optical fibers providing a pump-light to the first optical fiber in a direction parallel to the second optical fiber, the third optical fibers includes a multi-mode optical fiber having a fourth core; and a connector disposed between the first optical fiber and the second optical fiber, the connector being connected with the third optical fibers, that are disposed around the second optical fiber, and toward the first optical fiber, the connector including a third core connected between the first core and the second core, and a fifth cladding surrounding the third core, the fifth cladding connected between the first cladding and the third optical fibers, the third core having a diameter equal to that of each of the first and second cores.