Abstract: A micro-structured optical fiber suitable for supercontinuum generation, a preform therefor, and a method of production thereof and a supercontinuum light source. The optical fiber includes a core microstructured length section Lcm, which includes a micro-structured core region having at least a first region forming a central part of the core region and a second region surrounding the first region; and a cladding surrounding the core region; wherein the first and second regions are of a first and second silica material, respectively, which differs with respect to composition, and wherein the core region in at least a length part of the core microstructured length section Lcm has a cross sectional diameter Dcm perpendicular to the longitudinal axis which is about 8 ?m or less.

Abstract: An optical fiber having a longitudinal direction and a cross-section perpendicular thereto, the optical fiber includes a core region; and a micro-structured cladding region, the cladding region surrounding the core region and having longitudinally extending micro-structure cladding elements arranged in a background cladding material, the micro-structured cladding elements having cross-sectional sizes which are equal or different, at least a number of the cladding elements being arranged in a substantially two dimensional periodic manner or a Bragg-type of manner, such as concentric rings of cladding elements surrounding the core, and the at least a number of the cladding elements are filled in at least one longitudinally extending section of the optical fiber with a liquid crystal material. The at least one filled section exhibits a photonic bandgap effect for at least one phase state of the liquid crystal.