The self-consistent simulation of the modulation responses of quantum well lasers

A self-consistent simulation (called MINILASE) that solves simultaneously the electrostatic, carrier transport, and optical problems in all areas of the device has been developed and used to calculate self-consistent modulation responses for a laser diode. The frequency responses of three single buried quantum well GaAs/AlGaAs lasers, each with a different type of cladding region, have been compared. One cladding region has constant Al concentration; another has a quadratically graded Al mole fraction; and the third is linearly graded. The calculations clearly show that the modulation response can be improved by exploiting the gradient in crystal potential that accompanies a graded cladding region.