Patent ID: 7792161
Filing Date: 2010-09-07
Classification: G02B,H01S

Abstract:
1. An optical fiber for a fiber laser, comprising: a hollow core region; an inner cladding region comprising a plurality of holes that extend in a longitudinal direction of the optical fiber and surround the hollow core region; and an outer cladding region that is solid, without holes, and surrounds the inner cladding region, wherein the inner cladding region comprises a solid part that is made of a glass material into a part or all of which a rare earth element is doped and a diameter of each of the plurality of holes and intervals between the plurality of holes are set such that a band gap is formed with respect to a multi-mode oscillation wavelength of a laser beam and a transmission loss of a higher mode is larger than a transmission loss of a lower mode with respect to the oscillation wavelength of the laser beam, a distance from a hole located at an outermost portion of the inner cladding region to the outer cladding region is greater than a distance between adjacent holes in the inner cladding region, and the outer cladding region has a refractive index lower than that of the solid part of the inner cladding region.