The Holk: I don´t remember in wich presentation I read this, but when POET explained their supply chain they said that additional active and/or passive components will come "off the shelf" from yet to named suppliers.

Electronic components are off the shelf, active photonic devices have to have a specific “plug” in order to fit into the OI “socket”. Nothing spectacular, but it has to be done. So the supplier (here: the modulator supplier) has to make some commitment (and investment) into the technology.

Aside from that, there’s not much constraint on what you can plug into the OI. From the press release: “This unique, patented architecture allows devices of different types to be seamlessly integrated, both optically and electrically, onto a single chip.”