“…Low-frequency 1/f α -type noise is a typical excess noise that is a very sensitive measure of the quality and reliability of optoelectronic devices, as it is related with the defectiveness of the structure of the device (Jones, 2002;Lin Ke et al, 2010;Vandamme, 1994). Measurement of low frequency noise can indicate the presence of intrinsic defects as well as fabrication imperfections, which act as deep traps or recombination centres in semiconductor materials and their structures (Fukuda et al, 1993;Jones, 1994;Palenskis, 1990). This section presents noise characteristic analysis that was performed in order to clear up the origin of laser diode lower quality and degradation, factors that accelerate degradation, to find out noise parameter that could be used for LD quality and reliability prediction.…”