I did a quick look to see what it is they are building so far
400G QSFP-DD SR8 and 400G QSFP-DD DR4
I think there would be pretty much zero chance that the POET dielectric waveguide stack would be used in such an early application as it is based on doubling up the 200G optical engine with one on top of the other. Rather than a lateral layout of all die on a dielectric waveguide plane.
Unless you have found other applications and whitepaper that describes any uniqueness to the design that could provide some indication like the application of integrated CWDM.
And of course the obvious question we should ask now is do they have a presence in Allentown?