Low-frequency noise and quality prediction of MQW buried-heterostructure DFB lasers

摘要

A detailed study of both the optical and electrical low-frequency noise and correlation factor between optical and electrical fluctuation characteristics of single-mode multiple quantum wells (MQW) buried-heterostructure (BH) distributed feedback (DFB) laser diodes has been carried out under a wide current range. These techniques have been used to assess the structural differences between devices that exhibit superior and poor performance and reliability. It has been concluded that for the devices investigated here, the poor device performance characteristics (larger threshold current) and poor reliability are induced by the existence of defects in the interface between the active region and burying layer. These defects generate leakage currents that lead to the larger threshold current. Defects migration during ageing forms clusters, and this leads to the poor reliability of the lasers. We demonstrate that the low-frequency noise investigations can detect the presence of defects that induce short device lifetime.