摘要 |
A photonic crystal fiber including a plurality of longitudinal holes (220), in which at least some of the holes have a different cross-sectional area in a first region (200) of the fiber, that region having been heat-treated after fabrication of the fiber, from their cross-sectional area in a second region of the fiber (190), wherein the optical properties of the fiber in the heat-treated region (200) are altered by virtue of the change in cross-sectional area of holes (230) in that region (200). |