We have modeled the effect of compositional interdiffusion on the optical properties of GaSb/AlGaSb and InGaAsSb/AlGaAsSb quantum-well structures grown on GaSb substrate. Blue shifts of emission wavelength as large as 270 nm and 700 nm are predicted from a 6 nm wide interdiffused GaSb/AlGaSb quantum-well for a diffusion length of 3 nm, and from a 10 nm wide interdiffused InGaAsSb/AlGaAsSb quantum-well for a diffusion length of 5 nm, respectively. The effects of the as-grown quantum-well width and applied electric field on the emission wavelength and their relationship to the interdiffusion are also investigated. (c) 2006 Elsevier B.V. All rights reserved.