Quantenmechanik 11: Wie funktioniert ein Laser?

The laser is a development based on the findings of quantum mechanics. If, at the drop of a hat, lasers were no longer available, the world would plunge into absolute chaos. Why? Global high-speed data transmission via fiber optic cables is powered by lasers! This is an oversized model of such a fiber optic cable! But what is so special about this laser light, and how is it generated? And why does quantum mechanics play a role in this?