Expanding the surface-emitting laser rainbow

Research Project, 2025 – 2028

Compared to the maturity of today’s blue laser diodes, which exhibit high efficiencies, low threshold currents, and long lifetimes, ultraviolet-C (<280 nm) lasers have essentially just been born. We have only recently witnessed the first electrically driven ultraviolet-C (UV-C) edge-emitting laser. And more complex lasers, such as vertical-cavity surface-emitting lasers (VCSELs) are even further behind, having only been demonstrated under pulsed optical pumping. In this project, we aim to demonstrate the world’s first electrically driven UV-C VCSEL using our recent breakthroughs which are:Unique membrane technology to create low-loss cavities with accurate cavity length control, as demonstrated by our optically pumped UV-C VCSELs. The world’s first electrically driven resonant-cavity UV-B LED. This showed efficient horizontal current spreading thanks to the use of highly conductive n-doped material throughout virtually the entire laser, enabled by a tunnel junction. The only missing building block is a horizontal current confinement scheme, and we will here explore a few options in parallel such as buried tunnel junctions and implanted apertures. The expansion of the laser rainbow by UV-C VCSELs will offer a power-efficient, compact and low-cost light source for applications such as lithography, gas sensing and sterilization. The developed technologies will also benefit many other areas, such as photonic integration, micro-LEDs, and opto-mechanical resonators.