POLARIZATION-MAINTAINING OPTICAL FIBER, METHOD OF MANUFACTURING POLARIZATION-MAINTAINING OPTICAL-FIBER CONNECTING PORTION, AND POLARIZATION-MAINTAINING OPTICAL-FIBER CONNECTING PORTION

摘要

A polarization-maintaining optical fiber includes a core region and a cladding region formed around the core region. The cladding region has a refractive index lower than a refractive index of the core region. A refractive index profile of the core region is either one of a step shaped or a concave shaped. The cladding region includes two holes formed in such a manner that a shortest distance from the core region is virtually zero at locations in opposite to each other across the core region.