Science https://doi.org/gd3p56 (2018)

Spatiotemporal instabilities in broad-area high-power semiconductor lasers are troublesome and unwanted as they degrade laser performance. However, eliminating them is difficult. A team of scientists from the US, UK and Singapore has now discovered that such instabilities can be strongly supressed by the use of either D-shaped cavities that support chaotic ray dynamics or resonators that feature random refractive index fluctuations. In both cases, the formation of filament-type instabilities is prevented by interference between many waves with random phases and stable multimode lasing occurs. Such stable lasers could prove useful for applications such as materials processing or as high-power pump sources for fibre lasers and amplifiers. The research team says that the concept should also be applicable to other forms of lasers such as broad-area vertical-cavity surface-emitting lasers (VCSELs) and solid-state lasers.