Optical amplifiers with strained‐layer multiple quantum well active regions are shown to exhibit a bandwidth of 100 nm with a saturation output power larger than 25 mW. For a 780‐&mgr;m‐long device, the small‐signal gain exceeds 25 dB. The combination of high gain with large saturation output power is obtained by properly tailoring the mode confinement factor and differential gain coefficient of the strained‐layer gain medium.