Scientists and Engineers have used surface-emitting semiconductor lasers in data communications, for sensing, in FaceID and within augmented reality glasses. In a new report, Yong-Ho Ra and a research team in the departments of Electrical and Computer Engineering, and Advanced Electronics and Photonics in Canada, Korea and the U.S., detailed the first achievement of an all-epitaxial, distributed Bragg reflector (DBR)-free, electrically injected surface-emitting green laser. They optimized the device by exploring the photonic band edge modes formed in dislocation-free gallium nitride nanocrystal arrays, without using conventional DBRs. They operated the device at approximately 523 nm, with a threshold current of 400 A/cm2-an order of magnitude lower than previously reported blue laser diodes. The studies opened a new paradigm to develop low-threshold, surface-emitting laser diodes, ranging from the ultraviolet region to the deep visible range (approximately 200 to 600 nm). At this range, the device performance was not limited by the lack of high-quality DBRs, large lattice mismatch, or substrate availability. The results are now published on Science Advances.
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