Screening of high-power diode laser bars by optical scanning

Abstract

High-power diode laser bar arrays (808 nm) with very uniform emission properties are inspected by the laser-beam-induced current technique (LBIC). Setting the excitation energy to 50 meV below the lasing energy, we observe distinctive signatures within the LBIC scans at certain locations on the devices. After 1000 h of high-power operation, we observe degradation at exactly those positions that previously showed a characteristic LBIC signature. A cathodoluminescence analysis reveals that the quantum wells of these anomalous device sections suffer from the existence of spots with reduced luminescence efficiency. Additionally, a concomitant 2.3 meV redshift of the quantum-well cathodoluminescence spectrum is also observed. Our measurements demonstrate the efficiency of the LBIC approach as a screening tool as well as its capacity for predicting device failure well before any degradation of the emission properties is observed.