Lifetime tests of superluminescent diodes

The process of slow degradation of a batch of 48 superluminescent diodes (SLDs) with different active-channel lengths L_a (24 diodes with L_a = 600 μm and 24 diodes with L_a = 1000 μm) made of a heteroepitaxial wafer is studied. The diodes were divided into six groups, each containing eight diodes, and were tested at the stabilised injection current I = 140 mA and the heatsink temperatures 25, 55, and 70°C. The median lifetime of a SLD with L_a = 600 μm was 3000, 2450, and 1900 h at temperatures 25, 55, and 70°C, respectively. The calculated lifetime for a SLD with L_a = 1000 μm exceeds 100000 h at 25°C and is 53000h at 55°C and 30500 h at 70°C. The obtained results confirm that a perspective technical solution providing an increase in the lifetime of high-power SLDs is the design with non-injected ends of the active channel which reduces current and, hence, thermal loads.