Dutch-grown on-chip laser ready to shine

As we learn in high school, a basic laser works by oscillating light between two mirrors through an amplifying medium. As the photons bounce back and forth, they encourage the formation of exact ‘copies’ of themselves. This process, known as stimulated emission, not only serves as an amplification mechanism but is also responsible for the main characteristic that makes laser light so special: it’s coherent, meaning the photons are in phase in space and time. By having one spot on the mirrors partially transparent, some light is allowed to escape so we can use it for one of the many applications that have been developed for it.

In this basic setup, the laser’s optical cavity formed by the mirrors and the gain medium basically coincide. But there’s no reason why that should be. In fact, many different types of external-cavity lasers have been developed, some of which have been commercially available for a long time.