CONNECTION STRUCTURE FOR MULTI-CORE FIBER AND OPTICAL-FIBER-BUNDLE STRUCTURE, CONNECTION STRUCTURE FOR MULTI-CORE FIBERS, METHOD FOR EXCITING RARE-EARTH-DOPED MULTI-CORE FIBERS, AND MULTI-CORE-OPTICAL-FIBER AMPLIFIER

摘要

An optical-fiber-bundle structure is connected to one end of a multi-core fiber. The multi-core fiber has a tapered section formed therein. The outside diameter of the multi-core fiber and the core pitch thereof decrease in the tapered section. It is possible for the multi-core fiber to have an increasing core pitch on the connection-side thereof which connects to the optical-fiber-bundle structure; hence, it is possible to use an easy-to-use large-diameter optical fiber as the optical fiber to be provided in the optical-fiber-bundle structure. When connecting another multi-core fiber to the other end of the multi-core fiber, it is possible to match the outer diameters thereof; hence, when fusion splicing to one another, it is unlikely for a positional shift of the cores to occur.