Spectral photoconductivity curves are measured in reverse biased DH AlGaAs/GaAs laser diodes. In the band edge region where the absorption can be described by Franz-Keldysh theory a dip is observed, the position of which corresponds to the maximum of the edge emission. The dip is caused by an additional radiative recombination channel that decreases the lifetime of photocarriers in this region. The appearance of the dip is discussed in connection with the laser parameters. [Russian Text Ignored.]