I honestly believe that trying to apply silicon to advanced photonics applications ultimately amounts to putting lipstick on a pig. No offense intended to the pig. It can never be as good as using the specific material sets which provide for the most effective wavelength management for any given application.

I think Rockley's history is providing us with a good example of this. 

Again POET is applying the most advanced developments in hybrid evolution which the silicon industry has turned to for high end applications. The optical interposer is an inevitable extension of that development.