Numerical aperture optimization using doped cladding layers

摘要

A method and apparatus for optimizing the numerical aperture (NA) of a laser active core. The laser active core comprises at least a first and second cladding pair. The first and second cladding pair have at least one NA value. At least one of the first and second cladding pair is doped with a dopant to change the first NA value to a second NA value.