PHOTONIC BANDGAP FIBER AND FIBER LASER DEVICE USING SAME

摘要

Disclosed is a photonic bandgap fiber that is used in a state where at least a portion thereof is bent by 15 cm to 25 cm inclusive, wherein: a multitude of high refractive index parts (57) are arranged in three layers with a 19-cell-core structure; the V value is from 1.5 to 1.63 inclusive; and the conditions for the relative refractive index difference &Dgr;% and the grating constant Λ µm of the high refractive index parts (57) are determined such that higher modes are eliminated in portions bent as described above.