| 摘要 |
A residual light removal structure 70 is used to remove residual light in a double-clad fiber 40 having a core 60, a cladding 62 having a refractive index lower than a refractive index of the core 60, and a covering material 64 having a refractive index lower than the refractive index of the cladding 62. The residual light removal structure 70 has a fiber housing 72 that houses part of the double-clad fiber 40, a cladding exposure portion 74 in which part of the whole circumference of the cladding 62 is exposed from the covering material 64 along a longitudinal direction of the double-clad fiber 40, and a resin 76 filled within the fiber housing 72 so as to cover at least the cladding exposure portion 74. The resin 76 has a refractive index that is equal to or higher than the refractive index of the cladding 62. For example, the cladding exposure portion is formed with a range of angles less than 180° about an axis of the double-clad fiber 40 in a cross-section perpendicular to the axis. |
