Laser Materials

Abstract

As is well known, the word laser is an acronym for “light amplification by stimulated emission of radiation,” a phrase which covers most, though not all, of the key physical processes inside a laser. Unfortunately, that concise definition may not be very enlightening to the nonspecialist who wants to use a laser but has less concern about the internal physics than the external characteristics. A general knowledge of laser physics is as helpful to the laser user as a general understanding of semiconductor physics is to the circuit designer. From a practical standpoint, a laser can be considered a source of a narrow beam of monochromatic, coherent light in the visible, infrared, or UV parts of the spectrum. The power in a continuous beam can range from a fraction of a milliwatt to around 20 kilowatts (kW) in commercial lasers, and up to more than a megawatt in special military lasers. Pulsed lasers can deliver much higher peak power during a pulse, although the average power levels (including intervals while the laser is off and on) are comparable to those of continuous lasers.