Fiber preform with laser weld volume including ultraviolet absorbing constituent and method of manufacturing the same

A fiber preform comprising:

• a first preform end, a second preform end, and a longitudinal axis extending from the first preform end to the second preform end;
• an outer preform cladding through which the fiber longitudinal axis extends, the outer preform cladding comprising an inner cladding surface facing and disposed radially around the longitudinal axis;
• inner preform tubes coupled to the outer preform cladding at the inner cladding surface of the outer preform cladding, each of the inner preform tubes comprising (i) a tube axis extending therethrough parallel to the longitudinal axis of the fiber preform, (ii) an inner tube surface extending radially around the tube axis, and (iii) an outer tube surface facing away from the tube axis, and wherein the inner preform tubes collectively defining a preform core that extends radially from the longitudinal axis and that is tangential to the outer tube surface of each of the inner preform tubes;
• and
• first laser weld volumes, each of the first laser weld volumes fusing a different one of the inner preform tubes to the outer preform cladding,
• wherein, each of the first laser weld volumes comprises an oxide that exhibits an ultraviolet absorption tail within a range of from 200 nm to 400 nm.