POSEIDON aims to fabricate a demonstrator on-chip light source for data transmission or sensing on a PIC within a short time scale. After successfull integration, lasers can be created by coupling the emitters to nanophotonic resonators. The long-term vision of POSEIDON goes far beyond the creation of on-chip light sources. The aim is to establish a manufacturing platform for generic PICs consisting of monolithically integrated active colloidal components (light sources and detectors), combining silicon photonics and CMOS electronics. The benefits of POSEIDON can be quantum leaps in data center energy efficiency and network performance, enabled by the project targeting the usual Datacom wavelengths, and cheap yet powerful optical sensors.