A novel edge‐emitting periodic index separate confinement heterostructure (PINSCH) semiconductor quantum well laser is proposed and demonstrated for the first time. Periodic semiconductor multilayers are used as optical confinement layers to simultaneously reduce the transverse beam divergence and increase the maximum output power. Self‐aligned ridge‐waveguide InGaAs/GaAs/AlGaAs PINSCH quantum well lasers emitting at 980 nm are fabricated. The 5×750 &mgr;m device has far‐field angles of 10° by 20°, a threshold current of 45 mA, an external differential quantum efficiency of 1.15 mW/mA (90%), and an output power exceeding 620 mW, all measured at room temperature under CW operation. A record high fiber coupling efficiency of 51% has been achieved with a lensed fiber of 5 &mgr;m core diameter.