We carry out experimental research of power and spectral characteristics of semiconductor lasers at high excitation levels (up to 100 kA/cm2) in pulse operation (100 ns, 10 kHz). It is shown that the pump current increase gives rise to both a saturation of the peak intensity in stimulated emission spectra and emitted power raise due to spectrum extension in the short wavelength region. The limitation of stimulated emission rate is responsible for a saturation of the radiated power. We determine that it is just a finite energy scattering time of electrons on polar optical phonons that confines stimulated emission rate. We assume that the extension of stimulated emission spectrum is related to the increase of carrier density in the active region resulting in electron escape into the waveguide layers.
Carrier density in the waveguide reaches its threshold value with pump current increase resulting in an intensive current leakage from the active ragion.
We have shown experimentally the correlation between an onset of waveguide generation and considerable drop of differential quantum efficiency of semiconductor laser.
Физика и техника полупроводников, 2006, том 40, вып.