text: what exactly is a laser? how do they work?   laser is an acronym of light amplification by stimulated emission of radiation.  what this means is, the intensity of the light is increased via a process called stimulated emission.  the laser contains material called the laser medium, and when photons of light pass through this medium under conditions that are controlled by lenses within the laser, the medium gives up energy in the form of additional photons.  so the laser outputs a fine beam of highly energetic light as a result of a quantum mechanical process.