A nine‐unit phase‐locked array of index‐guided channel‐substrate‐planar large‐optical‐cavity AlGaAs diode lasers is fabricated by one‐step liquid phase epitaxial growth over a 5‐&mgr;m period sawtooth grating etched into a GaAs substrate. Two‐lobed, 180° phase shift operation is achieved to 75‐mW cw power and to 400‐mW peak pulsed power. Strong coherent optical coupling between the array units provides single‐longitudinal‐mode array operation to 80‐mW cw output power. The cw and pulsed threshold currents are in the 250–400‐mA range. Single‐lobe, 0° phase shift operation, with the single beam peaked at 0°, is achieved to 200‐mW peak power.