induced absorption

Induced absorption is a process in physics where a medium absorbs electromagnetic radiation, leading to a decrease in the intensity of light as it passes through. This absorbed energy is added to the medium. The degree of absorption can vary significantly across different regions of the electromagnetic spectrum.1

An abrupt increase in absorption as radiation frequency rises is known as an absorption edge, particularly observed with X-rays and linked to electron energy levels in atoms.2

The interaction of radiation with matter involves both absorption and emission. When an atom absorbs a photon, it moves to a higher energy state. Conversely, in spontaneous emission, an atom in an excited state releases a photon and returns to a lower energy state. A third process, stimulated emission, occurs when an existing photon triggers an excited atom to emit an identical photon, a principle fundamental to lasers. Lasers utilize stimulated emission to amplify light, producing monochromatic, directional, and coherent beams used in various applications, from telecommunications to industrial processes.34567