A fiber optic article can comprise a core, an inner region disposed about
the core and a cladding disposed about the inner region. The index of
refraction of the cladding can be less than that of the inner region, and
the index of refraction of the inner region can be less than that of the
core. The fiber can include a second cladding disposed about the
cladding, where the second cladding has an index of refraction that is
less than the index of refraction of the cladding. The inner region can
have a non circular outer perimeter that includes at least one inwardly
oriented section. The article can be elongate along a longitudinal axis
and can include at least one longitudinally extending region, such as a
stress inducing region, for providing birefringence and the inwardly
oriented region can face the longitudinally extending region. The fiber
optic article can include active material for providing light responsive
to the article receiving pump light, such as, for example, one or more
rare earths. The rare earths can include erbium and ytterbium.