Photonic memory moves closer to practical deployment

03 Dec 2025

Research builds on UW–Madison’s membership in AIM Photonics to advance system design.

One of the biggest obstacles to fully optical computing has been the lack of a fast, scalable photonic memory cell. Researchers at the University of Wisconsin–Madison have demonstrated what they are calling “a manufacturable photonic memory device that functions as an optical counterpart to traditional SRAM and addresses a long-standing gap in optical system design”.

Their design, which delivers write speeds near 20 GHz and read speeds up to 50–60 GHz, was developed in consultation with experts from AIM Photonics and GlobalFoundries to ensure it could be fabricated using standard silicon photonics processes, making it compatible with existing foundries and ready for volume production.

“Our solution only uses those components available in a commercial foundry,” said lead developer Akhilesh Jaiswal, a UW-Madison assistant professor of electrical and computer engineering. “We are not using exotic processes or materials. This design could be fabricated in volume today.”

The engineers say that their new photonic chip – which leverages parts and fabrication techniques already in use by established semiconductor foundries – could soon bring optical computing connectivity to data centers and high-performance computing systems.

The device was designed and tested by Jaiswal, alongside PhD student Md Abdullah-Al Kaiser, and colleagues at the University of Southern California Information Sciences Institute. The team is presenting its research at the International Electron Devices Meeting 2025, in San Francisco, next week.

“This memory can store light and operate at speeds beyond the reach of its electrical counterpart memory,” said Jaiswal. “This is the first ever solution that provides a viable pathway to a scalable photonic memory on a commercial foundry process that can be volume-manufactured right away.”

Background to development

In recent years, researchers and chip manufacturers have created optical computing systems, where laser pulses traveling at the speed of light are used for computation instead of electricity. However, researchers still need to figure out how to create optical analogues of all the necessary computer components. That means most optical systems are electrical-optical hybrids, in which signals are converted from light to electricity and back again, negating some of the advantages.

One critical component with no immediate practical optical alternative is memory, where information is stored or buffered before reaching a computer processor. Jaiswal and collaborators, have created their photonic memory using a design they call a cross-coupled, differential, regenerative photonic latch – “pLatch” – circuit. This uses a combination of tiny photodiodes, micro-ring resonators and optical waveguides. Together, the devices create an optical analog of SRAM, the type of memory used in electricity-based computer processors.

“In principle, it has all the same capabilities of the electrical SRAM, but is much faster,” said Jaiswal. “An electrical SRAM operates at two or three gigahertz. In our simulations, we see the pLatch operate at 20 gigahertz, and the read speed could be 50 or 60 gigahertz.”

A key drawback to the device, and one that affects photonic components in general, is its size. While electronic computer components have shrunk to the nanoscale, photonics are still at the micro level.

The size means optical computing cannot currently power processors inside cellphones or desktop computers. As large optical “interposers,” however, they are useful in linking many different processors. They can be used to tie together racks of servers in data centers to help them work in unison, and they offer a similar function in bringing optical speeds to the multi-processor systems used for high-performance computing and large-scale simulations.

While finding a unique solution to the optical computing bottleneck is an achievement, the team thinks the most important part of its circuit is its practicality. The researchers developed the design in consultation with cutting-edge chip fabrication firms AIM Photonics and GlobalFoundries, using their silicon photonics platform to fabricate the pLatch device.

“Our solution only uses those components that are currently available in a commercial foundry,” said Jaiswal. “We are not using exotic processes or materials. This design could be fabricated in volume today by companies like Global Foundries or other key semiconductor manufacturers, if needed.”