An active gain medium is a material that is used in creating optical amplifiers. It is used to amplify light signals by providing energy to photons in a stimulated emission process. Some common synonyms for active gain medium include amplifying medium, gain medium, and gain material. Another synonym is laser medium, as active gain mediums are often used in the creation of lasers. Other terms that can be used include active laser material, active medium, and active oscillator. Regardless of the term used to describe it, the active gain medium is a crucial component in many advanced technologies, including telecommunications, medicine, and scientific research.