Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 13

When a current pulse is applied to a laser diode, the injected carrier pair density n within the recombination region of width d changes with time according to the relationship
( a ) Assume is the average carrier lifetime in the recombination region when the injected carrier pair density is n th near the threshold current density J th. That is, in the steady state we have n/t = 0, so that
If a current pulse of amplitude I p is applied to an unbiased laser diode, show that the time needed for the onset of stimulated emission is
Assume the drive current I = JA, where J is the current density and A is the area of the active region.
( b ) If the laser is now prebiased to a current density J B =I B /A, so that the initial excess carrier pair density is n B = J B /qd, then the current density in the active region during a current pulse I p is J=J B + J p. Show that in this case Eq. (4.50) results.