Micro-transfer printing for heterogeneous Si photonic integrated circuits

Are you feeling nostalgic for homogeneous integration of chips—one flat board where you can use your fingers to stuff in all the circuitry you need? It might be best to head to the Lego store. The rest of the world is moving fast to heterogeneous integration—where the boards are 3D, the chips are a mix of electronic and photonic functions, and every specification is in nanometers. It just as challenging as it sounds, but much more fun.