This article discusses the characteristics common to laser diodes, such as high coherence, narrow spectral width and high directivity, while also explaining and defining these terms. Thus, threshold current is one measure used to quantify the performance of a laser diode. However, threshold. Laser diodes (LD) are semiconductor devices that convert electrical energy into high-power optical energy. Accordingly it is necessary to understand the main laser diode specifications and characteristics and how they can relate to real electronic. On the past few years, Authors have proposed and developed a model for laser diodes,,, based on a new version of the Rate Equations for photons and charges. This generates the Output Light vs.