Methods of and systems for processing using adjustable beam characteristics

An apparatus, comprising:

• an optical fiber usable in an optical beam delivery system, the optical fiber including:
• a confinement region having a refractive index arranged to maintain any selected beam characteristic from a set of two or more different beam characteristics;
• and
• a perturbation region to, in accordance with the selected beam characteristic of the set of two or more different beam characteristics, modify one or more beam characteristics of an optical beam by a perturbation assembly coupled to the perturbation region or integral with the perturbation region;
• wherein the confinement region preserves at least a portion of the one or more beam characteristics of the optical beam modified by the perturbation assembly;
• and
• wherein the perturbation assembly is selectively operable in a group of modes including:
• a first mode of operation that corresponds to a first beam characteristic of the set of two or more different beam characteristics and in which the optical beam modified by the perturbation assembly is arranged for generating a laser beam having a spot shaped beam profile, and a second different mode of operation that corresponds to a second different beam characteristic of the set of two or more different beam characteristics and in which an intensity distribution of the laser beam is moved radially outward relative to the first mode of operation.