Degradation of GaAs Diode Lasers

Gallium arsenide diode lasers degrade when too high a current density is passed through them. The degradation consists of a decrease in output optical power, an increase in the laser thershold current, and a decrease in the current-rectification ratio. Degradation occurs in both diffused and solution-grown junctions, for lightly doped junctions. The degradation occurs under pulsed operation at room temperature and continuous operation at low temperatures. If the duty cycle under pulse room-temperature operation is increased at a constant peak current, a value is reached beyond which degration occurs. For continuous lasers, efficient diodes are more prone to degration than poor diodes. Spectral measurements indicate that junction heating is negligible. These results are reminescent of degradation in GaAs tunnel diodes, and the failure mechanism may be similar.