  The planned IceCube Upgrade, consisting of seven new instrumentation strings,
will be installed at the South Pole within 2022/2023. The focus of this upgrade
is calibration, reduction of systematic uncertainties and atmospheric neutrino
physics. Within this scope, the "Precision Optical Calibration Module" (POCAM)
will be installed at a number of positions on these new strings, to act as a
calibration light source. The POCAM is an in-situ self-calibrating, isotropic,
nanosecond light source that emits flashes of adjustable intensity and pulse
duration. The isotropy is achieved using a teflon integrating sphere which
further allows the calibration of the total number of emitted photons per
pulse, using the integrated sensors. Prototypes have been deployed and operated
within the GVD telescope in Lake Baikal and within the STRAW experiment in the
Pacific Ocean. We present POCAM results and experiences from the GVD and STRAW
installations as well as first IceCube sensitivity studies and the following
design prospects for this next-generation POCAM iteration.
