Lasers, powerful beams of concentrated light used in everything from barcode scanners to eye surgery, rely on a surprisingly ancient phenomenon known as stimulated emission.

This concept describes the process where an excited atom, already in a higher energy state, encounters a photon of light with identical energy. The photon “stimulates” the atom to release a second photon, identical in energy and direction to the first.

This chain reaction of stimulated emissions leads to the amplification and coherence of light, resulting in the distinctive, focused beam we know as a laser. Imagine a chorus of singers all harmonizing on the same note – that’s akin to how stimulated emission creates a laser beam.

Prompt:
Think of a technological marvel that relies on a surprisingly simple, almost primitive, physical phenomenon for its operation. Describe this phenomenon and explain how it enables the marvel to function.