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exiting radii at this transition. A loading
is applied at a distance of 22mm from
the end of the module lid for all cases for
this strength requirement. We also did
account for the pre-bent free fibers inside
of the module and the model uses a
nonlinear large displacement analysis to
take into account the effects of geometry
changes during load application.
The configuration giving the smallest
stress level is the tapered boot with a Figure 15: Example of loading conditions considered on the pigtail exiting the module. The tapered boot
softer material, which reduced the stress design that was included in this study is shown.
by 17%. Also, the material variation
had more impact on reducing the stress
than the shape and therefore plays
an important role when the fibers are
deflected to the side. The pigtail retention
between the side pull and the axial
pull are totally different—Figure 16
represents the comparison between the
stresses calculated for a tapered oval boot
configuration with the softer material.
The stresses are normalized to the
maximum of the axial pull load case, and
a side pull load case that is 5.8x higher is
observed, indicating that this condition is
likely to be critical for the robustness of
the module. This result is consistent with
the experimental strength measurement
of the fiber in the V-groove experiments
where axial cases are significantly
stronger than shear cases.

Summary
Fiber optics integration in the first-
level package is required to enable
high-bandwidth demands for data
com mu nication. T he work in [1]
studied the best anchoring location of
a strain relief for fiber optics ribbon
in order to protect the photonic die
V-groove’s interconnect. The fiber
layout within the package between
the strain relief and the photonic die
uses fiber bending to compensate
for thermal and mechanical strain of
the package. An optimization of the
parameters permits the maintenance
and control of the fiber bends, thereby
alleviating the stress within the co-
package photonic device. RoHS
Our model has shown that longer P
lengths induce less stress and are easier
to facilitate bending. Also, with fiber
lengths below 8mm, the required bends
needed for strain relief would be past
the acceptable threshold limits for the
fiber and would create excessive stress
in the fiber. Also, the misalignment
in the fibers caused by the exit angle

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