The band gap of Ga0.47In0.53As corresponds to an emission wavelength of ∼1.65 μm. Lasers have been produced with Al0.48In0.52As as cladding layers operating at room temperature. The peak emission of Ga0.47In0.53As can be continuously varied from 1.65 to 1.2 μm by the use of the multiquantum well structures. This range of wavelengths covers the minimum loss and dispersion in optical fibers and will be applicable to integrated optics. Double heterostructure broad area lasers have been fabricated using AlInAs as cladding layers to the GaInAs active layer. Room temperature threshold current densities of 4.3 kA/cm2have been obtained for lasers with a 4500 Å active regions. The first data on GaInAs/AlInAs quantum well emitters will be presented. 4 K photoluminescence from quantum well layers of 100, 150, and 180 Å with 150 Å AlInAs barrier layers produced emission at 1.27, 1.35, and 1.41 μm, respectively. Ga0.47In0.52As quantum well LED’s have also been produced which emit at 1.34 μm.