By use of carbon doping tunnel junction which has a very high tunnel probability at reverse bias voltage,the distributing of the high concentration carbon doping layers in multi active layers poses high conductance layers and increases the transverse expanding current,so the laser can not act well.We use a novel double faced electrode structure to overcome the expanding of the transverse current and ensure the output light power of every cascade lasers.The means is to do a corresponding electrode alike the frontal one on the rear underlay of the conventional laser.When an electric field is put on,it is concentrated in the two electrodes and so the injection current can flow from the frontal electrode to the rear electrode without expanding.This means ensures the equal injection current for every active layer so that there have abundant output light power.To four active layers cascade lasers,the output light power can be promoted 70 % by contrast of lasers with conventional electrode.The output light power promotes form 1.6 W to 2.4 W.Slope efficency is 70 % more than usual devices.