They achieved this through exploiting the photonic band edge modes formed in dislocation-free gallium nitride nanocrystal arrays, instead of using conventional DBRs.
Surface-emitting semiconductor lasers have been widely used in data communications, sensing, and applications like Face ID and augmented reality glasses, using blue laser diodes. The device created by the research team delivered performance at over one order of magnitude lower compared to those existing blue laser diodes. The researchers' device operates at ~523 nm and exhibits a threshold current of ~400 A/cm2.
The researchers say this opens up a new paradigm for developing low-threshold surface-emitting laser diodes from the ultraviolet to the deep visible (~200 to 600 nm), where device performance is not limited by the lack of high-quality DBRs, large lattice mismatch, and substrate availability.
This low-threshold, high-efficiency, all-epitaxial surface-emitting green laser diode could enable emerging technologies, such as pico projectors, plastic optical fiber communication, wireless communication, optical storage, smart lighting, and biosensors.
Yong-Ho Ra and Zetian Mi from McGill University’s Department of Electrical & Computer Engineering conceived the ideas. Additional members of the research team were Roksana Tonny Rashid, Xianhe Liu, Sharif Md. Sadaf and Kishwar Mashooq.