BISOL Develops New Infrared Camera for Exoplanet Imaging

Researchers from Northwestern University's Bio-Inspired Sensors and Optoelectronics Laboratory (BISOL) developed a novel highly sensitive infrared camera that could help with directly imaging exoplanets orbiting in the habitable zone of nearby stars.

The corresponding paper, “InGaAs Based Heterojunction Phototransistors: Viable Solution for High-speed and Low-noise Short Wave Infrared Imaging,” appeared on the cover and as the editor’s pick in the April 2019 edition of Applied Physics Letters.

“This is an important development for making highly sensitive infrared imaging for a broad range of applications, such as medical imaging and autonomous cars,” said Mohsen Rezaei, PhD candidate in electrical engineering, who is the first author of this work.

The pixels in this camera are engineered by researchers at BISOL to amplify the optical signal by about 1,000 times at thousands of frames per second. This leads to a tremendous imaging sensitivity and speed needed for new discoveries.

“Scientists have been switching to II-VI material in order to produce fast infrared cameras with high sensitivity. In this work, we demonstrated that infrared cameras based on III-V semiconductors — which are much cheaper and safer material compositions compared to II-VI materials — have the capability of reaching similar quality as their II-V counterparts at much lower cost and higher operating temperature,” Razaei said. “Our camera operates at temperatures that are readily accessible by the very compact and nonmechanical thermoelectric coolers, while II-IV imagers with similar sensitivity need cryogenic cooling.”

Research at BISOL spans many subfields of optoelectronics, and the lab’s researchers have been the front runners in developing new concepts in optics, optoelectronics, and optical materials.

"We have been fascinated with this new technology since it can surpass some of the biggest challenges in infrared imaging,” said Hooman Mohseni, AT&T Professor of Information Technology and professor of electrical and computer engineering. “In addition to our goal of exoplanet imaging, my team is now utilizing the fundamental knowledge we have gained here to make ultra-fast medical imaging systems and ultra-low power optical interconnect on silicon chips."

This work was supported by the W. M. Keck Foundation under a Research Grant in Science and Engineering, and by partial funding from ARO award #W911NF-18-1-0429.