Delay time between the current pulse and the light emission of GaAs laser diodes

The delay time td between the onset of the current pulse and that of the light emission has been measured above threshold as a function of the diode current I for several GaAs laser diodes at a temperature of about 77° K. When plotted against In [I/(I¿Ith)], td decreases with increasing current, but does not obey the linear relation found by others. The values of td measured near threshold are in satisfactory agreement with the spontaneous emission time calculated from theory. Although the measured curves are all of the same shape, differences of td exist among the diodes, which are supposed to be caused by the presence of traps.