The planned IceCube Upgrade, consisting of seven new instrumentation strings, will be installedat the South Pole within 2022/2023. The focus of this upgrade is calibration, reduction ofsystematic uncertainties and atmospheric neutrino physics. Within this scope, the "PrecisionOptical Calibration Module" (POCAM) will be installed at a number of positions on thesenew 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 calibrationof the total number of emitted photons per pulse, using the integrated sensors. Prototypes havebeen deployed and operated within the GVD telescope in Lake Baikal and within the STRAWexperiment in the Pacific Ocean. We present POCAM results and experiences from the GVDand STRAW installations as well as first IceCube sensitivity studies and the following designprospects for this next-generation POCAM iteration.