We demonstrate a high-power AlGaAs single quantum well graded-index separate confinement heterojunction laser grown by molecular epitaxy over channeled substrates. Fundamental mode operation up to 130 mW for reflection modified devices has been achieved at a high differential quantum front-facet efficiency of 81%. This device structure allows extremely low threshold currents to 6 mA for power lasers due to the incorporation of lateral current blocking pn junction by crystallographic plane-dependent doping of amphoteric dopants. We obtained a very high-power continuous-wave fundamental mode operation of this type of laser at extremely low threshold currents and very high overall efficiency of more than 50%. This laser shows considerable potential for applications in optical storage and printer technology.