A different approach to the analysis of data in life-tests of laser diodes

A different reading of the available I–V curves is proposed for laser diodes whose characteristics display some degradation. In particular, the usual monitoring of the optical power P and of the threshold current I_th is complemented by the inspection of two more parameters, which separately or jointly contribute to the general variation of I_th. These two parameters are related to the simplest laser model, made of an ideal diode that is voltage-clamped under operating conditions, and are completely defined by those same standard measurements that lead to evaluate I_th. A different definition of the failure modes, and a deeper insight in the possible failure mechanisms are derived. Combined voltage and optical power monitoring during constant-current life-tests is also proposed as a more discriminating measurement than usually considered.