Influence of reflectivity on the external quantum efficiency of GaAs injection lasers

The differential external quantum efficiency η
ext
of Fabry-Perot-type GaAs injection lasers has been measured as a function of the mean reflectivity
R
. By evaporation of antireflective films,
R
has been varied between 0.25 and 0.06. The observed increase of η
ext
with decreasing
R
is interpreted in terms of a simple model. Values for the optical losses α, the gain factor β, and the internal quantum efficiency at 77°K are obtained for individual diodes.