An illumination system for biological applications, wherein the system employs at least one nanostructured optical fiber. The fiber is preferably wound around a support structure to form a light-source fiber portion where guided light is scattered from the fiber outer surface to form an extended light source that emits substantially uniform radiation. The bends in the light-source fiber portion are formed to enhance the amount of scattering in the nanostructured fiber. Counter-winding the at least one fiber serves to increase the uniformity of the radiation by countering the effects of decreasing emitted radiation along the length of the light-source fiber portion. Multiple fibers wound in sequence around a support structure, with each fiber coupled to the light source, can be used to form a lengthy extended source. The light-source fiber portion can be configured to suit a variety of biological chamber geometries.