Printing optical chips as a layer cake

https://phys.org/news/2022-03-optical-chips-layer-cake.html

"silicon nitride wafer containing the passive components of the ultimate chip is produced with an extremely flat and clean top layer... release layer of material is grown. This is topped with the indium phosphide layer containing the active components such as lasers, optical amplifiers or photodetectors. The release layer underneath is then etched away, leaving behind a series of very small anchors that hold the separate devices in place. Then the thin indium phosphide coupon is picked up"