A research team of electrical and computer engineers at the University of Virginia and University of Texas-Austin have developed an avalanche photodiode, achieving record performance, that could transform receiver components for lidar. The innovation has been published in Nature Photonics.
The team used the novel optical and electrical characteristics of a digital alloy created at UT-Austin’s Laboratory for Advanced Semiconductor Epitaxy. This breakthrough springs from a longtime collaboration between University of Virginia engineering professor Joe C. Campbell and UT-Austin professor Seth Bank, who used molecular beam epitaxy to grow the alloy of aluminum, indium, arsenic, and antimony. The alloy combines long-wavelength sensitivity, ultra-low noise, and the design flexibility to achieve low dark currents, which is not available with existing low-noise avalanche photodiode materials technologies.
The new avalanche photodiode is an ideal solution for compact, high-sensitivity lidar receivers. Many lidar applications—robotics, autonomous vehicles, wide-area surveillance and terrain mapping, for instance—require high-resolution sensors to detect greatly attenuated optical signals reflected from distant objects. Eye safety has limited the deployment of such systems, though, because the requisite high laser power poses an increased risk of eye damage.
Professor Campbell says “The 2µm window is ideal for lidar systems because it is considered eye-safe and extends the detection reach. I can envision our avalanche photodiode impacting numerous key technologies that benefit from high sensitivity detectors.”