The well-known method of photocurrent spectroscopy, i.e. the measurement of the spectral sensitivity of a laser diode like for a detector, was found to monitor aging properties of (In)AlGaAs/GaAs high power laser diode arrays (LDA) in a convenient way. Photocurrent spectra of LDAs emitting at 808 nm (1.53 eV) were measured in the 0.8 - 3.0 eV photon energy range. Aging induced changes in different spectral regions reveal the influence of different mechanisms affecting the structure. Conclusions on the microscopic nature of the changes are drawn and applications are discussed.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.