Near-field characterization and failure analysis of broad-area laser diode with optical feedback

Optical feedback may cause accelerated degradation as well as catastrophic optical damage in high-power Laser diodes, directly limiting their output optical power and lifetime. Near-field distribution change caused by optical feedback has high relevance with the reliability and is worthy to be studied. In this study, the influence of optical feedback on the near-field distribution of the laser diode is investigated, as well as the influence on the device failure. A feedback light testing system is successfully established, which integrates power monitoring, spectral measurement, and near-field assessment. Through an investigation into the influence of feedback light, it was observed that it induces instability in the near-field distribution, leading to temporal variations. Under conditions of strong feedback, a stable near-field peak emerged. At even higher current levels, a clear correspondence was identified between the near-field peak and the point of failure. These findings offer valuable insights for the understanding of the influence of optical feedback on the nearfield distribution of the laser diode and its reliability.