You can make light turn on command, like water in a hose — if you know where to squeeze. That's what electro-optic circuits do: they change the direction of a beam inside a chip using an electric field. The classic material for such tricks is lithium niobate, a crystal that responds to voltage like a string to a pluck. But until now, it had to be sliced into ultra-thin films and glued onto other wafers — expensive and finicky.

The new work sidesteps that hassle. The researchers grew a layer of amorphous silicon carbide right on a thick piece of lithium niobate — no films, no bonding, no etching of the crystal itself. The result is a monolithic platform: light travels through the silicon carbide, while the lithium niobate underneath controls it. This sandwich is compatible with standard microelectronics fabs where processors are made, meaning it can be stamped out cheaply by the millions.

Record efficiency—2.87 volt-centimeters — means a battery can drive the switching, not a bulky power supply. The circuit itself takes up less than a square millimeter. Such chips could link servers in data centers, sending data as light instead of electricity — faster and without overheating.

Once, optical chips seemed like an expensive toy for labs. Now light is learning to race along cheap crystalline paths, like electricity along copper wires, but faster.