This chapter provides an overview of long wavelength metamorphic
quantum well lasers. The idea of metamorphic growth is to
compromise large lattice mismatch by utilizing a relaxed buﬀer
layer. Structural design and growth optimization of metamorphic
buﬀer layers are reviewed with emphasis on composition grading
scheme and doping eﬀects. Progress on long wavelength (>1.2 μm)
metamorphic quantum well lasers is summarized.