What type of active medium is used in Er: YAG lasers?

The active medium used in Erbium:YAG (Er:YAG) lasers is a solid-state crystal matrix, specifically a crystal composed of yttrium aluminum garnet (YAG) doped with erbium ions. This type of laser operates by the stimulated emission of photons as the erbium ions within the YAG matrix are excited by a pump source, typically a flashlamp or diode laser.

The solid-state nature of the Er:YAG laser allows it to be compact and robust, making it suitable for various applications, including medical procedures, dentistry, and cosmetic surgery. The interaction of the laser light with biological tissues is characterized by its wavelengths (around 2940 nm), which are efficiently absorbed by water in tissues, allowing for precise and controlled tissue interaction.

Gas mixtures, liquid dyes, and fiber optics represent different technologies and mediums that are used in other types of lasers. Gas lasers utilize gaseous mixtures as their active medium, while dye lasers use a solution of organic dye as the medium. Fiber lasers utilize optical fibers that contain a doped core, typically made of glass, which can amplify light. However, none of these options apply to the specific mechanism of the Er:YAG laser.