A passing photon interacts with an already excited electron, triggering it to release an identical photon—sharing the same phase, frequency, and direction.
For a laser to function, it must achieve , where more atoms exist in an excited state than in a ground state. Without this imbalance, incoming photons would simply be re-absorbed rather than multiplied. Essential Components of a Laser NIF's Guide to How Lasers Work Lasers: fundamentals and applications
An atom absorbs an incoming photon, causing an electron to jump to a higher energy level. A passing photon interacts with an already excited
Laser operation is governed by quantum mechanics and three primary interactions between light and matter: Essential Components of a Laser NIF's Guide to
An excited electron naturally drops to a lower state, releasing a photon in a random direction and phase.
Lasers, an acronym for , generate intense beams of coherent, monochromatic light through a cascade of photon "cloning" . Since their invention in 1960, they have evolved from a "solution in search of a problem" to a foundational technology in modern science, medicine, and industry. Fundamental Physics: How Lasers Work
