It is very different and can't scale anywhere near what hybrid solutions can. Yield is the issue because you don’t get to throw away failed components (one die). Thermal constraints are a huge issue with opposing requirements between the two domains. Materials have to coexist and silicon provides limited photonic properties. Microrings have to be heated to stabilize the wavelength which is really counterintuitive.

POET=best material set for each active device, layout freedom for designers.  

The ecosystem for POET is massive as companies who build specific devices have a market to supply POET with the best of breed.