MULTI-CORE FIBER AND METHOD OF POSITIONING OF CORE OF MULTI-CORE FIBER

摘要

A multi-core fiber for accommodating multiple single mode cores in one optical fiber is provided with multiple types of non-identical cores having different propagation constants. Each of the multiple types of non-identical cores includes a core part and a cladding part covering an outer periphery of the core part. The cladding part has a double cladding structure including a first cladding for surrounding an outer periphery of the core part and a second cladding on the outer side of the first cladding. In the multiple types of non-identical cores, an optical electromagnetic profile in the core part and the first cladding is confined within a range of the core part and the first cladding, restricting a leakage thereof to the second cladding, and the propagation constant of each non-identical core is made different using the refractive index of the first cladding as a parameter. With this configuration, while the cores become denser by increasing the number of types of the non-identical cores, the range of the relative refractive index difference ” between the non-identical cores is allowed to be restrained, further mitigating the increase of difference in the propagation characteristics between each core.