Gain-Switched Pulse Response of Quantum-Well Lasers

An analytical model is established for the gain-switched pulse response of quantum-well lasers (QWLs). The electron and photon rate equations are coupled through the dynamic variations of the laser gain represented by the stimulated lifetime in terms of the Fermi energies. The gain switching response is obtained analytically using approximate quiescent boundary conditions and a perturbation technique which enables solution of the differential equations. A theoretical sech²(t) pulse shape for the photon response is obtained analytically for the first time. The condition for obtaining identical repetitive pulses is discussed and found to be determined by both the electrical direct current (dc) bias and alternating current (ac) pulse amplitude and width. The analytical solution is shown to be excellent by comparison to a numerical solution of the standard equation. To establish the utility of the model, pulse data on vertical cavity surface emitting lasers (VCSELs) were taken and found to be well predicted within the error of the measurement.