A large optical cavity diode laser has been developed operating at 1070 and 1118 nm using partially strain-balanced DQW gain regions of GaAs0.94P0.06/InxGa1-xAs (x = 0.24 and 0.29). TEM has been used to characterise the QWs for interface roughening resulting from the high residual compressive strain. For both wavelengths, oxide-defined stripe-contact devices show comparable slope efficiencies and T-0 values. In the case of the 1070 nm laser. the operating lifetime at 15degreesC was in excess of 4600 h for an output of 1.5 W and degradation rate of 2 x 10 (5)/h. (C) 2002 Elsevier Science B.V. All rights reserved.