Imagine trying to build a computer that thinks using flashes of light instead of electricity — but there's one big problem: light never slows down. You can't hit pause on a beam of light the way you might buffer a video on your phone. That single limitation has held back a whole field of technology called optical computing for years. But now, a team of engineers in South Korea may have cracked the code.
Researchers at Seoul National University have built a tiny chip — about the size of a fingernail — that can slow light down on command. Led by Professor Namkyoo Park and Professor Sunkyu Yu from the Department of Electrical and Computer Engineering, the team worked with Professor Xianji Piao from the University of Seoul to design a programmable photonic integrated circuit. Their work was published June 30 in the journal Advanced Science.
The chip uses something called coupled-resonator-induced transparency, or CRIT for short. Think of it like a series of tiny mirrors arranged in a circle that catch and release light in a very specific way. By adjusting how these tiny mirrors interact with each other, the team can make light speed up, slow down, or even change color — all in real time, and all by reprogramming the chip rather than building a new one.
This matters because the world is running out of ways to make traditional computers faster. As artificial intelligence programs grow larger and more demanding, the standard silicon chips inside our laptops and phones are hitting physical limits — they use too much energy and generate too much heat. Optical computers, which process information using light instead of electricity, could be much faster and use far less power. But without a way to delay or store light signals, they couldn't perform basic functions like synchronizing data or temporarily holding information — what engineers call "buffer" and "memory."
Previous designs could slow light, but only at fixed speeds, like having a car that could only drive at one speed. The new chip from Seoul National University is more like a car with a real gas pedal — researchers can adjust how much delay they want and shift it to different colors of light, all by turning digital knobs on the circuit. This flexibility could dramatically shrink the size and cost of equipment inside data centers, the massive warehouses that power cloud computing and AI.
The team demonstrated that their programmable design could delay light and modify its frequency characteristics depending on how the circuit was controlled. By treating two optical states — called the bright mode and dark mode — as a single unified system with two adjustable loop couplers, they achieved a level of control that earlier methods couldn't match. In other words, they turned what was once a rigid, one-note instrument into a fully tunable one.
While the results come from simulations so far, the team is working to build and test physical prototypes. If the technology scales as expected, it could help bring optical computing out of laboratories and into the data centers that keep the internet running — potentially making AI faster, cheaper, and more energy-efficient in the years ahead.