Two thin-clad laser diodes are disposed to form a stack-type diode laser device. The diodes emit two beams that are substantially parallel and in proximity such that they share many fiberoptic systems designed for a single beam. The diodes are coupled by leaky waves through top surfaces. The leaky waves are generated by a thin metal contact layer or diffractive gratings. The stack-type device is employed for single-mode power enhancement and tunable lasers.