One possible configuration of the Rockley platform: Light is generated from an external III-V continuous wave laser which couples to the silicon photonics chip which I expect contains the MUX/DEMUX (to preserve real-estate and for thermal isolation) then the SiP couples to the ASIC and from the ASIC the fiber is said to have a 500 meter reach. All coupling is achieved by fiber coupling to waveguides. POET extends the waveguides across all devices in a microfabrication flow.