Patent ID: 8452145

Claim:
A triple-clad optical fiber comprising: a core, a first inner cladding, a second inner cladding, and an outer cladding wherein, the core comprises a radius of less than about 5 μm, a first index of refraction n 0 and does not contain any rare-earth dopants; the first inner cladding surrounds the core and comprises a radial thickness of at least 10 μm, a numerical aperture of at least about 0.12, and a second index of refraction n 1 such that n 1 <n 0 , wherein a relative refractive index percent(Δ%) of the core relative to the inner cladding is greater than about 0.07%; the second inner cladding surrounds the first inner cladding and comprises a radial thickness of at least 8 μm, a numerical aperture of at least about 0.20, and a second index of refraction , wherein a relative refractive index percent (Δ%) of the second cladding relative to the outer cladding is greater than 1%; the outer cladding surrounds the second inner cladding and comprises a radial thickness of at least 10 μm and a third index of refraction n 3 such that n 3 <n 2 , and n 3 <n 1 .