Researchers in the ScopeX Lab and the Yao Group are harnessing the power of the photon for accelerated AI modeling and novel infrared detection, respectively.
The ScopeX Lab works at the intersection of photonic circuit simulation and high-performance photonic circuits for artificial intelligence.
"We're trying to co-design circuit architecture and algorithms for high-performance photonic AI systems," Jiaqi Gu, the principal investigator for the ScopeX Lab and a professor in the School of Electrical, Computer and Energy Engineering, said.
A photon, a massless fundamental particle of light, can be used in place of electrons in circuits. Circuits that use photons rather than typical electrons are known as photonic circuits.
"A photonic (integrative circuit) does not operate on any electric signal, like currents or voltage. They work with light," Gu said.
Photonic circuits have several advantages in performance compared with traditional electronic circuits. The photons arrive significantly faster at the final destination than electrons and use considerably less power and energy compared to electronic circuits, Dennis Yin, a graduate student studying computer engineering and research assistant at ScopeX lab, said.
Due to the fundamental nature of light, researchers are also able to encode more information into a signal than would normally be transmitted by electrons alone, Gu said. He added that the signals allow for not only more power-efficient computation but also faster, more information-rich data transfer.
"(Light) carries a lot of information in its magnitude (and) phase," Gu said. "Most importantly, you can see multiple optical signals can coexist on the single photonic waveguide, carrying different colors (and) different polarizations."
Despite the benefits of using photonic systems, several challenges remain to be overcome. There are non-ideal qualities in noise pollution and cross-talk between communicating components, and the photonic systems are also physically larger than common transistor-based systems, Yin said.
Photonics can be used in a wide array of applications. According to Gu, the market for optics is already larger than the market for electronics, though the optical market is more spread out and less unified.
ScopeX focuses primarily on the application of photonic systems in high-performance AI. However, photonic technology can be used in multiple domains, from data communication to virtual reality lenses and biosensors.
While ScopeX is working on using light for computation, the Yao Group is studying how light can be used to see wavelengths undetectable to the human eye.
The Yao Group is developing a device that senses mid-infrared light through the use of phononic crystals at room temperature.
The mid-IR region of the electromagnetic spectrum contains light with wavelengths longer than are visible to the human eye. This mid-IR region contains information on the atomic structure of materials and can be used to sense objects without visible light being present, Zengyu Cen, a graduate student studying electrical engineering and research assistant with the Yao Group, said.
The mid-IR sensor is comprised of a phononic crystal, a structured material that manipulates mechanical vibrations. The sensor also includes an engineered material that turns the incoming mechanical vibrations from the infrared-induced motion of the phononic crystal into heat, which can then be measured.
Together, the ScopeX Lab and the Yao Group are showing how light can be used not only at the forefront of computation but also in sensing the invisible.
"This is going to make a very big influence in medical imaging and diagnosis and semiconductor characterization to detect some defects on the top surface of the materials," Cen said. "That's what we are doing from the device level to the system."
Edited by Kate Gore, Senna James and Pippa Fung.
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John Tamayo is a science and technology reporter in his first semester with The State Press. He is a senior majoring in Physics and Philosophy.
