Radiance of small-area high-current-density electroluminescent diodes

Optical power radiated into a solid angle per unit area of emitting surface (radiance) is a basic measure of the usefulness of an electroluminescent device to be used as a communications-system source. Dc radiance values from about 20 to more than 100 W/sr/cm
²
have been obtained for various small-area GaAs and AlGaAs diodes operated at current densities that yielded an operating half-life of at least several thousand hours. These radiance values are two to three orders of magnitude larger than those obtained with relatively large-area commercial light-emitting diode (LED) indicator lamps.