The quickest and most cost-effective way to run these lasers is by connecting two or more laser diode current sources in parallel to produce the necessary drive current. These devices are currently used in the fields of telecommunications and medicine and in industrial cutting and welding applications. This article discusses the characteristics common to laser. A laser diode (LD, also injection laser diode or ILD or semiconductor laser or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction. As an example, five watts of fiber-coupled, pump laser light may require six.