Recent research indicates that light-emitting diodes (LEDs) as narrow as a human hair may soon perform tasks traditionally reserved for lasers. This includes applications such as data transmission within server racks and powering next-generation display technologies. The study, co-authored by UC Santa Barbara doctoral student Roark Chao, outlines a promising approach for the implementation of these devices.
Chao, who is pursuing a doctorate in electrical engineering, emphasised the significance of these microLEDs: “We are discussing devices that are essentially the size of a hair follicle. If we can refine the way light is emitted, these microLEDs could replace lasers in short-distance data communication.” This research builds upon UC Santa Barbara’s established expertise in gallium nitride research and optoelectronics.
Chao is co-advised by Steven P. DenBaars and Jon A. Schuller, both of whom are co-authors of the study. The research also includes contributions from Nobel laureate Shuji Nakamura, renowned for his groundbreaking work on blue LEDs that revolutionised lighting and display technologies globally. The research was conducted within the laboratories of the DenBaars/Nakamura and Schuller groups, focusing on gallium nitride materials and nanoscale photonics.
Published in Optica Express, the study showcases an innovative design for microLEDs that enhances both efficiency and beam directionality. By laterally enclosing the emitting region with distributed Bragg reflectors, the researchers achieved approximately 20% higher optical output through air-side emission, over 130% higher output through the substrate side, and a 30% reduction in beam divergence compared to conventional devices.
The enhanced design not only improves light direction but also significantly boosts efficiency. The team recorded around 35% higher electrical efficiency and approximately 46% higher wall-plug efficiency, indicating that these devices convert a considerably greater proportion of the power consumed into usable light compared to standard microLED designs.
MicroLEDs, typically measuring 100 microns or less in width, are emerging as a viable alternative to lasers for short-range optical communication, particularly in data centres where issues such as heat generation, reliability, and energy consumption are prevalent.
Chao noted, “Lasers tend to encounter thermal problems at relatively low temperatures. In contrast, microLEDs can operate at much higher temperatures without necessitating complex cooling solutions. This results in lower replacement costs and greater flexibility within data centres.” As cloud computing and artificial intelligence continue to grow, the demand for efficient and rapid data transmission increases. Even minor advancements in light sources could yield substantial economic benefits.
“What is particularly thrilling about microLEDs is their versatility; they provide multiple solutions within a single technology,” Chao added. “They can enhance data communication, facilitate brighter and thinner displays, and even be applied in augmented reality (AR) or virtual reality (VR) systems, all leveraging the same fundamental technology.”
Chao’s journey at UCSB began as an undergraduate electrical engineering student in 2020, progressing to his current doctoral research. He attributes the university’s comprehensive research infrastructure—encompassing materials growth, nanofabrication, and device testing—as a catalyst for his progress.
“The ability to simulate a design, grow the crystal, fabricate the device, and conduct testing—all within the same campus—is what makes this environment exceptionally powerful,” Chao remarked. “This rapid transition from concept to experimentation is a significant advantage.”
The findings of this research are detailed in a paper co-authored by Chao, Stephen Gee, Alejandro M. Quevedo, Wesley K. Mills, Tanay Tak, Hunter S. Larson, Kent N. Nitta, Nakamura, Schuller, and DenBaars.