Low nonlinear gain in InGaAs/InGaAlAs separate confinement multiquantum well lasers

We have determined the differential gain, nonlinear gain factor, spontaneous emission factor, and the K factor for InGaAs separate confinement multiquantum well lasers with InGaAsP and InGaAlAs barriers using a new parasitic‐free modulation technique. We find that the nonlinear gain factor e is more than four times, and the K factor more than two times lower for lasers with InGaAlAs barriers than for those with InGaAsP barriers. This strongly suggests that InGaAs/InGaAlAs lasers are more suitable for high bandwidth applications.