In this overview we want to introduce the IceCube Neutrino Observatory. In part I we focus on the input of KIT and DESY for the developments of SiPM-readout scintillation detectors for an extended surface array of IceCube and IceCube-Gen2. in part II we show the developments of optical sensors for the IceCube Upgrade.

IceCube is a unique detector, not only due to the discovery of very high energy cosmic neutrinos, but also as a multipurpose research facility. It also contributes to cosmic ray physics, dark matter searches and glaciology, and is therefore most suitable for multi-messenger astroparticle physics.