If you are looking for an example of how POET's Optical Interposer architecture is applied to Celestial it is represented in the lower right corner. External Laser solution using the Optical Interposer.

Celestial uses a Silicon Photonics wafer with the ASIC mounted on top and the PIC functions as an interposer with EIC connected. 

It is a big space and POET can’t expect to fill all multi-chip packaging solutions but they do excel at the ones they are focused on. Optical engines using modulated lasers like DML and EML (applicable directly for 800G/1.6T and beyond) and Remote laser solutions (to support the Si Photonic fabrics or Thin Film Lithium Niobate fabrics).