Patent ID: 8229260

Claim:
An optical fiber apparatus for having an increased optical power threshold for avoiding damage to the apparatus, comprising: an optical fiber mode field adapter having an input and an output, said mode field adapter transforming optical energy from a fundamental mode having a smaller mode field diameter at the input to a fundamental mode having larger mode field diameter at the output, said mode field adapter including: a length of optical fiber comprising a core including a taper wherein the cross sectional area of the core increases; a cladding disposed about said core for tending to confine light to the core so as to be guided by the core; a region disposed about the cladding, said region comprising a material contactingly disposed about said cladding and having an index of refraction that is greater than an index of refraction of said cladding by a selected amount, said region stripping optical energy from said cladding, the selected amount being no greater than 0.035; and a second region disposed about and in optical communication with said region, the second region for one of reflecting or absorbing optical energy stripped from said cladding by said region.