As computers become faster, light seems like the ideal medium because nothing travels faster. Yet high-speed computing depends not only on speed but also on precise timing. Although scientists can control the flow of light, today’s photonic hardware is typically built for one fixed design and operating speed. The challenge is finding a way to make light arrive earlier or later using the same chip.
Researchers from Seoul National University and the University of Seoul developed a programmable photonic chip that can dynamically adjust light-pulse delays, bandwidth, and frequency response after fabrication.
Although the technology has so far been demonstrated only through theory, numerical modeling, and electromagnetic simulations, the team believes it could provide essential functions such as synchronization, buffering, and signal processing for future optical computers and ultra-fast communication networks.
The Growing Need for Light-Based Computing
Unlike conventional CPUs and GPUs, which transmit information as electrical signals carried by electrons through metal connections, photonic systems use light. As modern processors and AI workloads continue to grow, electrical interconnects consume more power and increasingly limit data bandwidth.
Instead of transmitting data with electrons, photonic technology encodes information into light. Because photons travel at extremely high speeds and produce much less resistive heat, they offer a promising alternative for handling massive amounts of data.
However, the fastest possible speed is not always ideal for computing. Signals often follow different routes and complete different operations before they must be combined, so they need to arrive at precisely the right moment. That requires delaying, synchronizing, buffering, and filtering optical signals—tasks that electronics performs well but photonics finds more difficult. While light itself cannot be slowed down, its arrival time can be delayed.
One existing solution is coupled-resonator-induced transparency (CRIT). It uses tiny optical resonators that trap specific light frequencies and allow their waves to interact. The resulting interference creates a narrow transmission window where selected frequencies pass through with a controlled delay, much like a carefully engineered roundabout that slows traffic so vehicles reach their destination on schedule.
The Limitations of Fixed Photonic Circuits
CRIT systems can make light signals arrive at precisely the right time, but they lack flexibility. Once the resonators and their connections are designed for a particular function, their performance is largely fixed. Factors such as operating wavelength, transmission bandwidth, and delay are determined by the resonator geometry and coupling configuration. Changing these properties often requires manufacturing an entirely new chip.
The researchers from Seoul propose a more flexible approach: making the photonic circuit programmable. Their design incorporates tunable components that allow the same resonator network to be reconfigured after fabrication. CRIT architectures generally use two optical states called bright and dark modes. The bright mode interacts strongly with incoming light, while the dark mode interacts more weakly and can retain optical energy for longer periods. Their interaction produces the characteristic transmission and delay effects.
The proposed architecture combines these two modes into a single controllable system and adds two tunable loop couplers to the resonator network. Adjusting the couplers changes the interactions between the resonators, allowing the same circuit to generate different optical responses. The researchers could tune the transmission band, light efficiency, and optical pulse delay.
A Single Chip for Multiple Optical Functions
Numerical simulations further suggested that the delay could be modified dynamically while the circuit was operating. The system could also alter the frequency of transmitted light, potentially reducing the need for separate frequency-conversion components. This versatility is one of the concept’s key advantages. A programmable resonator network could handle multiple functions, including signal delay, filtering, and processing.
However, a design that works perfectly in theoretical models can face significant challenges when it is actually manufactured.
The researchers modeled the design on a silicon-nitride photonic platform and used 3D electromagnetic simulations to account for real-world imperfections such as material losses, backscattering, coupling variations, phase errors, and thermal crosstalk.
The researchers found that the architecture remained effective despite manufacturing imperfections, suggesting it could be built with existing technology. If experimentally validated, it could synchronize, delay, filter, and convert optical signals for communications and photonic AI systems.
A New Approach to More Flexible Photonic Circuits
According to Seoul National University’s Prof. Namkyoo Park, the study is important because it introduces a new design approach that allows the movement of light through photonic integrated circuits to be reconfigured when needed, significantly increasing their flexibility.
The researchers’ next step is to fabricate the device and test it experimentally, with the longer-term goal of developing larger programmable photonic circuits. So far, the concept exists only in theory and simulations, but the results indicate that it could be physically realizable. Making light delays programmable could advance more flexible light-based computing.
Read the original article on: newatlas
Read more:The world’s fastest-warming continent bakes beneath a record-breaking heat dome
