Image Courtesy: Xinhua News
Chinese researchers have created a silicon photonic device that enables a single beam of light to exist in three stable states instead of the conventional binary “on” and “off,” marking a significant step toward more powerful photonic computing systems.
The breakthrough was achieved by researchers from Peking University and Harbin Engineering University, who demonstrated tristability inside a silicon photonic crystal microcavity measuring just 20 micrometers in diameter, thinner than a human hair. Their findings, published in Nature Nanotechnology, could pave the way for optical computers capable of processing and storing far more information than today’s electronic systems.
Traditional computing relies on binary logic, where data exists as either a 0 or a 1. By allowing light to maintain three distinct stable states, researchers can significantly increase the amount of information stored and processed by a single optical component. This capability is considered an important milestone in the development of practical photonic computing and optical data storage.
One of the biggest challenges has been that light’s nonlinear effects become extremely weak on micro- and nano-scale chips, making stable multistate operation difficult to achieve. To overcome this limitation, the team employed a technique known as near-exceptional-point coupling, which strengthens the interaction between two resonant modes inside a photonic crystal microcavity.
The researchers fabricated a microcavity with an exceptionally high quality factor of one million, allowing light to circulate repeatedly before gradually dissipating. The system achieved clear tristability while requiring only 240 microwatts of switching power, less energy than a typical laser pointer. The team also demonstrated a prototype multi-valued optical memory device based on the new mechanism.
By precisely adjusting the input optical power or wavelength, the device can switch rapidly and reliably between its three stable states. The researchers believe this approach offers a practical way to harness light’s nonlinear behavior within ultra-compact silicon chips.
The achievement could provide a key building block for future optical neural networks, neuromorphic processors, and next-generation photonic computers capable of handling increasingly complex artificial intelligence workloads while consuming significantly less power than conventional electronic hardware.
