The major types of AlGaAs high-power cw single-mode diode lasers are reviewed and compared. The basic approaches for achieving high power (20-50 mW/facet) single-mode operation are presented first. Emphasis is placed on the CDH-LOC laser type, which has demonstrated cw single-mode operation to 40 mW/facet, and 50%-duty-cycle fundamental-mode operation to 100 mW/facet. By using CDH-LOC devices signal-to-noise ratios close to 70 dB were achieved, and peak powers of 40 mW (50% duty cycle) were coupled into 0.2 NA fibers. Lifetests of CDH-LOC lasers at 40 mW/facet initial output power and 50% duty cycle, have shown small drops in output even after 10,000 hours of operation. Monolithic ten-unit arrays of CDH-LOC lasers delivering up to 300 mW in cw operation have been demonstrated as well.