MONITORING OF AGING PROPERTIES OF ALGAAS HIGH-POWER LASER ARRAYS

Aging properties of AlGaAs high power laser arrays were monitored by p hotocurrent (PC) measurements. We demonstrate that this method allows a quantitative analysis of the aging process and provides insight into the microscopic degradation mechanisms. In graded index separate conf inement heterostructures, the PC spectra in the spectral range of the laser transition display a substantial current decrease with aging. Th is is attributed to enhanced rates of surface recombination and defect generation in the graded gap region. In contrast, step index structur es exhibit a much smaller change of PC. The PC results are complemente d by measurements of low-frequency laser current noise and front facet temperature. (C) 1997 American Institute of Physics.