Programmable photonic chip slows light for optical computing
Researchers say a reconfigurable optical circuit could help light-based computers synchronize signals and cut hardware complexity.
By Tom Brennan · Health & Medicine Correspondent
3 min read
Researchers in South Korea have designed a programmable photonic chip that can slow optical signals on demand, a capability they say could help make optical computing more practical. The work targets a basic problem in light-based systems: fast signals still need timing control, buffering and synchronization.
The Seoul National University College of Engineering said the project was led by Namkyoo Park and Sunkyu Yu of Seoul National University with Xianji Piao of the University of Seoul. The study, by Seungkyun Park, Beomjoon Chae and co-authors, was published in Advanced Science.
Optical computing uses light rather than electrical current to move and process information. Seoul National University said interest in the field has grown as AI models and data centers demand more computing power while conventional electronic chips face speed and energy constraints.
Light can transmit information quickly, but that creates a control problem. According to the researchers, optical circuits need ways to delay signals so different streams of information arrive at the right time, and those delay functions are needed for optical buffers and memory-like operations.
How the chip controls light
The team built its approach around coupled-resonator-induced transparency, or CRIT, an optical effect in which interference among resonators lets certain frequencies pass while slowing the signal. Optical resonators are devices that confine or circulate selected light frequencies for short periods.
Seoul National University said conventional CRIT devices tend to have fixed behavior after fabrication. If engineers need another delay time or frequency range, they often must create a different device, adding cost and complexity to optical communication hardware.
The researchers proposed a programmable version by treating two optical states in CRIT systems, called bright and dark modes, as a single design parameter. They also added two adjustable loop couplers, which the study says allow the circuit to change its delay, passband shape, bandwidth and transmission behavior.
In theoretical work, the team showed that the device could adjust how long optical pulses are delayed and how efficiently they move through the circuit. Seoul National University said numerical simulations also indicated that pulse speed could be changed while the circuit is operating, without reducing processing performance.
The study also reported that the system could convert light frequency without separate specialized components. That could allow one chip to combine functions such as signal synchronization, tunable delay lines, optical buffering and frequency conversion, according to the university.
Simulated on a silicon nitride platform
The researchers tested the design through three-dimensional electromagnetic simulations on a silicon nitride photonic integrated circuit platform. Seoul National University said the simulations considered practical problems including material losses, resonator differences, backscattering, coupling changes, phase errors and thermal crosstalk.
The university said those simulations suggested the structure could operate reliably under realistic manufacturing and operating conditions. The work remains pointed toward implementation, with the researchers saying they plan experimental validation and larger programmable photonic integrated circuits.
Park, a co-corresponding author, said in a statement that the study offers a design principle for reconfiguring light flow inside photonic integrated circuits and that the group plans to extend the work toward silicon photonics and photonic AI systems. Co-first authors Seungkyun Park and Beomjoon Chae said the team aims to develop the concept into practical devices.
Seoul National University said the technology could eventually help AI servers and data centers process information more efficiently by reducing the need for multiple fixed optical components. The university also cited possible uses in optical communications, sensor systems, autonomous driving, next-generation communications and quantum technologies if the approach is commercialized.
The research received support from South Korea’s Ministry of Science and ICT through the Innovative Research Center program, the Basic Research Laboratory program and the Young Researcher Program. Seungkyun Park also participated with support from the InnoCORE program at the PICORE Center.
This story draws on original reporting from ScienceDaily.