‘No Resistive-Capacitive Delays’: Researchers at Argonne and Purdue Develop All-Optical Switch

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Scientists at Argonne National Laboratory have created a “bimetallic” optical switch with the potential to bring dramatic efficiencies to how data is transmitted and stored, according to a recent announcement from the lab.

“The light-activated switch could bridge the gap between optical and electronic communications,” the lab stated in an article by Jared Sagoff, an ANL public information officer. “All-optical switches have the potential to increase the speed of computer processors by being triggered with light instead of electricity. Scientists at Argonne have designed an all-optical switch with multiple switching speeds, enabling data storage and transmission simultaneously.”

“When you use optical components instead of (conventional) electronic circuits, there are no resistive-capacitive delays, which means that in theory you could operate these chips a thousand times faster than conventional computer chips,” said Argonne’s Soham Saha, one of the lab’s Maria Goeppert Mayer postdoctoral fellows working in the Argonne Center for Nanoscale Materials. Optical I/O advocates also say the technology requires significantly less electric power.

The R&D work was conducted by researchers at Argonne and Purdue University. “Previous iterations of optical switches had fixed switching times that were ‘baked in’ to the device upon its fabrication,” said Saha.

He and his colleagues made an optical switch out of two different materials, each with a different switching time. One material, aluminum-doped zinc oxide, has a switching time in the picosecond range, while the other material, plasmonic titanium nitride, has a switching time more than a hundred times slower, in the nanosecond range.

Soham Saha, Argonne National Lab

The difference in switching times between the two metal components means the switch can be more flexible and used to both transmit data quickly while also storing it effectively, according to Saha.

“The bimetallic nature of the switch means that it can be used for multiple purposes depending on the wavelength of the light that you use,” he said. “When you want slower applications, like memory storage, you switch with one material; for faster applications, you switch with the other one. This capability is new.”

In the experimental configuration, the materials of the switch function as light absorbers or reflectors, depending on the wavelength of operation. When they are switched on by a light beam, they switch state.

Controlling the speed of all-optical switches is crucial for optimizing their performance in various applications. These findings offer promise for the development of adaptable and efficient switches in fields like enhanced fiber optic communication, optical computing and ultra-fast science. The ability to adjust switch speeds also could bridge the gap between optical and electronic communications, enabling faster and more efficient data transmission.

A paper based on the research, “Engineering the temporal dynamics of all-optical switching with fast and slow materials,” appeared in the September 21 online edition of Nature Communications. In addition to Saha, Argonne authors include Benjamin Diroll and Richard Schaller. Also contributing from Purdue University are Mustafa Goksu Ozlu, Sarah N. Chowdhury, Samuel Peana, Zhaxylyk Kudyshev, Zubin Jacob, Vladimir M. Shalaev, Alexander V. Kildishev and Alexandra Boltasseva.

The research was funded by the DOE’s Office of Basic Energy Sciences, as well as the Office of Naval Research and the Air Force Office of Scientific Research.