An optical fiber with a plurality of holes

An optical fiber 10 can efficiently excite metallic ions by a pump lightwave, and an optical fiber amplifier and an optical fiber laser light source both incorporate the optical fiber. The optical fiber 10 comprises (a) a solid region that has a first region [Figure 2A, 12] doped with metallic ions and a second region [Figure 2A, 13] surrounding the first region and that allows a lightwave for exciting the metallic ions to travel in a multiple mode and (b) a third region [Figure 2A, 16] surrounding the second region and having a plurality of holes [Figure 2A, 15] stretching along the length of the optical fiber. The optical fiber 10 has a structure in which the first region is supplied with the power of a lightwave that is included in the pump lightwave and that is in a mode having no intensity peak at the center axis of the solid region. The optical fiber may be formed by twisting.