A structure utilizing an exponential tapered active layer to improve the saturation output power and quantum efficiency of a traveling-wave semiconductor laser amplifier is discussed. Both the spatial distributions of the carrier density and the optical field are considered in the analysis. It is shown that an optimum taper geometry for maximizing the efficiency exists and that this structure provides simultaneous improvement in the saturation output power (7 dB) and the quantum efficiency (1.5 times) compared to a conventional device.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>