Abstract: A optically-pumped semiconductor (OPS), vertical-cavity, surface-emitting laser (VCSEL) includes a first mirror having a quantum-well structure thereon which provides a gain medium for the laser. A second mirror is spaced apart from the quantum-well structure and, together with the first mirror, forms a resonant cavity for the laser. Optical pump-radiation is directed through the gap into the quantum-well structure via an outermost layer of the quantum-well structure. The quantum-well structure includes a plurality of quantum-well layers spaced apart by pump-radiation absorbing layers. Quantum-well and pump-radiation absorbing layers are aluminum-free layers of alloys of the GaAs/InGaAsP system.