POET is developing short range optics...coherent modules are for long range communication, as near as I can tell...
Users of Coherent optical Modules
Long-haul Optical Transport Network (OTN) networks were the traditional users of coherent modulation. Cloud scale data centers have become an important consumer of coherent optical modules, particularly in the Ethernet connectivity space for reaches greater than 10 km where the advantages of coherent modulation can outweigh the increased cost.
https://en.wikipedia.org/wiki/Coherent_optical_module#Users_of_Coherent_optical_Modules