It is a semiconductor-based PN junction device that converts electrical energy into light energy similar to LED. It generates a high-intensity coherent and monochromatic light (single color). The emitted radiations have the same frequency and phase or sometimes very narrow bandwidth. 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. In such a heterostructure of a bipolar interband laser, electrons and holes can recombine, releasing the energy. There are now many applications for visible and UV continuous wave lasers in the tens to hundreds of milliwatts power range, covering e.
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