  A prime objective of modeling optical fibers is capturing mode confinement
losses correctly. This paper demonstrates that specific modeling choices,
especially regarding the outer fiber cladding regions and the placement of the
computational boundary, have significant impacts on the calculated mode losses.
Our results illustrate that one can obtain disparate mode confinement loss
profiles for the same optical fiber design simply by moving the boundary to a
new material region. We conclude with new recommendations for how to better
model these losses.
