ABSTRACT
Semiconductor laser diodes are key components in optical fiber communication, data storage, sensing, material processing, and other applications. This chapter examines basic formulas for optical gain and optical losses in semiconductor lasers, followed by the introduction of key performance parameters, threshold current, and slope efficiency. The current flow through the laser diode as well as nonradiative recombination processes generate heat inside the laser and elevate the internal temperature distribution. This temperature rise more or less affects all material parameters. The gain peak determines the emission wavelength of FP lasers, and it redshifts with higher temperature. But the gain peak also declines, so that more carriers are needed to maintain the lasing threshold. The distributed feedback (DFB) laser is widely used in single-mode fiber optic applications. Typical DFB lasers exhibit a periodic longitudinal variation of the refractive index within one layer of the edge-emitting waveguide structure.
