Generalized expressions for the turn-on delay in semiconductor lasers

In semiconductor injection lasers the time delay between the application of a step function in current and the onset of lasing is widely used to extract the carrier lifetime. In this paper the common analysis of this effect is generalized to include the case in which radiative recombination significantly modifies the time delay. Expressions appropriate when a dc prebias is applied are included. Previously untreated ambiguities of interpretation of experimental data are discussed, and the possibility is suggested that time-delay measurements can be used to separately extract the radiative and nonradiative contributions to the lifetime.