A laser diode (or diode laser) is a semiconductor device that undergoes stimulating emission to emit coherent light. They consist of a p-n semiconductor junction, with a forward bias voltage applied. 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. When electric current flows through the p-n junction, the gain is. A laser diode (semiconductor laser) is an electronic component that generates laser light by converting electric current into light using a semiconductor p-n junction. As a light source with excellent directivity and rectilinear propagation that enables easy control of energy, laser diodes are used. A laser diode is a small semiconductor chip that converts electrical current directly into a focused beam of light.