population inversion: Quick Facts

Written and fact-checked by

The Information Architects of Encyclopaedia Britannica

Photos

three-level laser

four-level laser

See All Images →

Topics

laser energy level transition excitation optical pumping stimulated emission How does a laser work?electronic configuration metastable state Franck-Hertz experiment Aufbau principle absorption edge

Italian-born physicist Dr. Enrico Fermi draws a diagram at a blackboard with mathematical equations. circa 1950.

Physics and Natural Law

Italian physicist Guglielmo Marconi at work in the wireless room of his yacht Electra, c. 1920.

All About Physics Quiz