A laser diode is a semiconductor device that transmits coherent and highly focused light through a process called stimulated emission. As a result, the beam profile of edge emitting diodes is unique when compared to all laser sources. Beam Diameter: The beam diameter refers to the diameter of the laser beam measured at the exit face of the laser housing. The 1/e 2 width is the distance between the two. The laser diode chip is the small black chip at the front; a photodiode at the back is used to control output power. These gadgets track down wide applications because of their proficiency and minimal size.