Fractional cladding for optical fibers

An optical fiber system comprising:

• an optical fiber having a doped core, a first cladding about the doped core, and a second cladding partially covering the first cladding such that the first cladding is exposed longitudinally, the optical fiber having at least a first longitudinal portion and a second longitudinal portion, the optical fiber being arranged such that the first longitudinal portion and the second longitudinal portion are longitudinally side by side with an exposed portion of the first cladding of the first longitudinal portion being adjacent to an exposed portion of the first cladding of the second longitudinal portion such that light propagating in the first cladding can move laterally from the first longitudinal portion to the second longitudinal portion to increase the amount of light reaching the doped core, the optical fiber adapted to be coupled to a power input to receive a light input and having an output end for outputting light emitted by the doped core;
• and
• at least one contour fiber having an index of refraction as a function of the optical fiber, the at least one contour fiber covering further exposed portions of the first cladding of the doped core fiber to conceal light in the first cladding.