Researchers in Japan have developed a small silicon optical modulator, a device that turns electrical signals into light signals. It transmitted data at up to 200 gigabits per second. Such devices could help AI data centers move large amounts of information between chips without increasing energy use. The new device measures just 0.32 millimeters long, compared with 2–4 millimeters for conventional silicon Mach-Zehnder modulators.
A pattern of tiny holes guides light through the silicon and slows it down. This makes the light interact more strongly with the device, so a small electrical change produces a larger change in the light signal. However, electrical resistance limits how quickly slow-light devices can respond. The researchers added a built-in equalizer, which adjusts the signal to improve performance at higher speeds. Using four light-signal levels, they reached 180 gigabits per second without digital signal processing. An additional equalizer at the receiving end raised the speed to 200 gigabits per second.
The compact design could allow more optical connections in data centers while limiting energy consumption. However, considerable light is lost as it passes through the device. The team used an optical amplifier to strengthen the light during experiments. Future improvements include reducing this loss and expanding the range of light wavelengths the device can handle.
