A new photonic chip architecture makes it possible to control the apparent speed of light signals within a circuit. Researchers can modify the delay and shape of these signals on demand. This could simplify certain components required for optical communications and future data centers, resulting in better performance at a lower energy cost.
In a classical photonic chip, information flows in the form of light pulses. They move very quickly, but this speed sometimes becomes an obstacle. Circuits need to delay, synchronize, or temporarily store signals so that their different parts can work together.
The researchers relied on a phenomenon called coupled resonator-induced transparency. Several resonant structures interact with light and modify its propagation. The signal therefore does not simply travel from one point to another: it acquires a controllable delay.
Thus, the chip can be reconfigured to produce several optical responses, instead of being limited to a fixed function determined during its manufacture. An undeniable advantage.
This mechanism could be used to create variable delay lines. These components are useful for synchronizing data, temporarily storing information, or adjusting the operation of optical networks.
Data centers dedicated to artificial intelligence are increasingly using optical connections. Light quickly transports large amounts of information, but systems still need to manage delays and exchanges between components. A reconfigurable chip could reduce the number of specialized devices, resulting in faster processing and reduced energy consumption.
This is of course not about stopping light or exceeding the physical limits of its propagation. The slowdown described concerns the group velocity and the delay of a pulse in the circuit. Additional work will be necessary before integration into industrial systems.