I would caution that posts proclaiming completion of the "prototype" in 2019 may be over-optimistic.
From Slide 24 of the AGM ppt:
Platform building blocks for 400G on track for completion in 2019
﹘Lasers, PIN Detectors, FR4 Filters, and Optical Interposer
2020 1H: Strategic Customer Product Development and Qualification
﹘ Chip-scale photonics integration for 400G TxRx
﹘ Wafer-scale assembly & test
2020 2H: Assembled Product Qualification / Supply Chain Readiness