ABSTRACT
The debut of semiconductor lasers came in a simple format of Fabry–Pérot (F–P) cavity with two cleaved facets as parallel mirrors. The light is generated in the active region typically made of multiple quantum wells (MQWs) through the radiative recombination of electron and hole pairs provided by the n- and p-cladding layers, respectively. Like most semiconductor lasers incorporating with an optical gain medium which consisted of a material that absorbs incident radiation of target wavelength, the electrons inside the material can be excited to nonequilibrium of unstable higher energy level under either optical or electrical driven pumping, leading to relaxation processing back from excited states to a lower level via radiative transitions. The past realization of room-temperature continuous-wave (CW) operation of lasing behavior of nitride-based lasers offered the possibility for nitride-based vertical-cavity surface-emitting lasers (VCSELs), to be applied to high-density optical storage device through the digital versatile disc platform.
