6. Glossary

stimulated emission

Process of interaction between a photon and an excited atom (or ion) whereby the incident photon triggers the de-excitation of the atom, accompanied by the emission of a photon in the same mode as the incident photon. This mechanism is responsible for optical amplification and lasers.

beam quality

Refers to the ability to focus a light beam onto a small area with a given divergence. It can be quantified in various ways, including by the M ² factor or by the size-divergence product. Brilliance is given by the power divided by the size-divergence product.

double-clad fiber

Optical fiber with two concentric cores, one guiding the signal to be amplified and the other guiding the pump used to excite the...