4. Glossary

Prohibited zone; gap

The energy range within which no electronic states can exist in a crystalline solid. It is the energy gap between the valence band and the conduction band.

Optical cavity

A system consisting of two or more mirrors arranged in such a way as to confine and cause light to resonate between them through multiple reflections.

Laser diode

It is a P-N junction diode that, when a sufficient electric current flows through it, produces stimulated emission of photons within a resonant cavity, thereby generating an amplified, directional beam of light with a precise wavelength.

Population inversion factor

It depends on the properties of the gain medium. It allows one to assess the degree of population inversion...