Ion-implanted vertical cavity surface emitting lasers are analyzed by photocurrent spectroscopy. The photoelectric quantum efficiency of such a device was found to reveal information on the presence of defect levels within the device. Photocurrent spectra of the samples, that are in part aged, were measured. For aged devices we find up to a tenfold increase of the magnitude of a defect band energetically situated below the laser emission. We show that photocurrent spectroscopy, that so far has been successfully applied for studying aging properties of high-power diode lasers, has also a remarkable potential as analytical tool for vertical cavity surface emitting lasers.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.