Digitally graded active region for optically pumped intersubband lasers and nonlinear wavelength convertors

A strategy is proposed for the realization of quantum-well structures optimized for devices based on intersubband optical transitions. It relies on the recently established techniques for the design of optimal smooth quantum-well profile by using the inverse spectral theory, followed by the design of an (almost) equivalent digitally graded structure, comprising just two different alloy compositions. Digital grading greatly simplifies the structure growth while essentially fully retaining the properties achieved in smoothly graded optimized structures. Example designs are presented for an optically pumped quantum-well laser and for a quantum well intended for the second-harmonic generation. © 2002 American Institute of Physics.