We report on the molecular beam epitaxy (MBE) growth and luminescence properties of tensile-strained type II GaAs/GaSb 1− x As x (0 x 1− y Sb y alloyed quantum wells (QWs) or self-organized formation of quantum dots (QDs). Both QW and QD nanostructures exhibit bright photoluminescence in the 1.5–2.2 μm range. AlGaSbAs laser diodes with GaAs/GaSb nanostructures in the active region have also been fabricated. The laser diode incorporating a 1.1 ML-GaAs/13 ML-GaSb superlattice in the active region shows room-temperature lasing at a wavelength of 1.85 μm under pulsed mode operation.