Baba, I may be a bit of a techie and somewhat knowledgeable in certain things, but I certainly wouldn't call myself a knowledgeable techie when it comes to POET'S OI platform.  LOL

That said, there may be some confusion on the distinction between the "OI platform" and a transceiver optical engine, the latter being a variant of the platform itself.  Rather than try and explain my interpretation, it's probably best to go straight to the source, the company's website found here:

The POET Optical Interposer™

I will admit to being somewhat uncertain what Vivek actually means when he states the platform is ready for mass commercialization, my guess is that the company's initial OI based 100G and 200G transceiver engines are ready for mass production, and the factory is fully configured and ready to go.

To answer your question about transmit (Tx) only, receive (Rx) only and combined TxRx.  I believe the company has perfected a full optical engine with combined TxRx for 100G and 200G applications, these will be the optical engines that are incorporated into a module maker's working transceiver and first off the JV's assembly line.

Last we heard, the company had completed 400G Rx and rumour has maybe even completed the 400G Tx as well.  Is it possible to sell an Rx or Tx only optical engine, the answer is sure, but I have no idea what the market is for these as stand alone items, perhaps module makers or data centre customers may have a specific use. Someone knowledgeable in data centre architecture may be able to answer this.

I think it's a fair to say that the ultimate goal for the 400G optical engine is to have the combined TxRx solution, both functionalities combined into a single chip, or perhaps separate Rx and Tx chips adjacent to one another within a transceiver.  Obviously, everything on one chip is the ideal solution.