Scientists have achieved the first continuous wave laser at room temperature from a deep ultraviolet laser diode.
A research group led by 2014 Nobel Prize winner Hiroshi Amano at the Institute of Materials and Systems for Sustainability (IMaSS) at Nagoya University in central Japan, in collaboration with Asahi Kasei, Inc. has successfully performed the world's first continuous-wave laser emission from a deep-ultraviolet laser diode (wavelength to the UV-C region) at room temperature. The results, published in Applied Physics Letters, represent a step forward in the practical implementation of a technology with potential for a wide range of applications, including sterilization and medicine.
After decades of research and development since their introduction in the 1960s, laser diodes (LDs) have finally been successfully commercialised. examples of this technology include optical communication devices using infrared LDs and blue-violet optical discs using blue-violet LDs. However, despite long and tireless efforts by research groups around the world, no one has been able to develop deep ultraviolet LDs. now, researchers from Nagoya University and Asahi Kasei have modified the structure of the device itself to reduce the driving power required for the laser to operate at room temperature by just 1.1 W. In earlier devices, the laser streak tended to cause crystal defects to occur, preventing an efficient current path from being generated and the laser from operating at a high power. In this study, the researchers found that strong crystal strain caused these defects. So by cleverly clipping the sidewalls of the laser streak, they suppressed the defects and achieved an effective current flow to the active region of the laser diode, reducing the operating power.
The research is a milestone for the practical application and development of semiconductor lasers in all wavelength ranges. In the future, UV-C lasers could be used in healthcare, virus detection, particle measurement, gas analysis and high-definition laser processing, with potentially ground-breaking applications in sterilisation technology.
