Optical combiner, laser device, and method for manufacturing optical combiner

A method for manufacturing an optical combiner that includes an optical fiber bundle formed by a plurality of first optical fibers and a second optical fiber, the method comprising:

• joining together an end surface of the optical fiber bundle and an end surface of the second optical fiber by fusion-splicing, wherein
• the plurality of first optical fibers includes a predetermined first optical fiber and other first optical fibers,
• the predetermined first optical fiber is composed of at least one material having higher softening temperatures than at least one material of the other first optical fibers,
• the predetermined first optical fiber includes a first core and a first cladding,
• the second optical fiber includes a second core and a second cladding,
• the first core and the second core are joined to each other by the fusion-splicing,
• respective cross-sections of the first optical fibers are deformed by softening during the fusion-splicing, and
• a cross-section of an end surface of the predetermined first optical fiber that is joined to the end surface of the second optical fiber is deformed less than cross-sections of end surfaces of the other first optical fibers that are joined to the end surface of the second optical fiber.