Just as a reminder what it is that Juniper is building for a 400G pluggable module is 400G QSFP-DD.

Which is a 50g lambda requiring 8 lanes. DD = double density was originally a transition from 200g which was doubled. 

And just as a reminder POET has built the first AWG mux demux which means it is the next generation of 400G utilizing CWDM which only requires 1 lane. 4X100g on a single path at 4 different wavelengths on the same fiber. And as we have been told typical silicon photonics optical engines have coupling + transmission loss in the 50% range. 

If they have managed to reduce losses by 20% that would be good.