“…Laser diode is the most common type laser with a wide range of uses that include fiber optic communications, laser pointers, CD/DVD reading and recording, laser printing, laser scanning and increasingly directional lighting sources. The laser diode can be either edge emitting [31,32] or surface emitting (which is also called vertical cavity surface emitting laser, or VCSEL) [33], depending on the form of cavity. Usually, a VCSEL has smaller threshold current but many more layers to form the vertical cavity, as shown in Fig.…”