On the current dependence of the injection efficiency and the relative contribution of the escape rate and internal optical loss to saturation of the power–current characteristics of high-power pulsed lasers ($\lambda$ = 1.06 $\mu$m)

The results of numerical simulation of the current dependence of the efficiency of injection into the active area of a laser based on separate-confinement double heterostructures are reported. The feature of carrier transport through isotype $N$–$n$ heterojunctions at the interface between the waveguide and active areas is demonstrated. Using the classic dependences of the Drude–Lorentz theory, the electron $(\sigma_e)$ and hole $(\sigma_p)$ scattering cross sections for a GaAs waveguide are estimated. Using the obtained values of $\sigma_e$ = 1.05 $\times$ 10$^{-18}$ cm$^2$ and $\sigma_p$ = 1.55 $\times$ 10$^{-19}$ cm$^2$ and the current dependences of the injection efficiency, the primary cause for confinement of the pulse power of the semiconductor lasers is determined. It is established that the internal optical loss is a minor fraction of the loss and the decisive contribution to saturation of the power–current ($P$–$I$) characteristics is made by the escape of holes to the waveguide.