In order to study the current transport of the novel semiconductor laser diode, which has several active regions cascaded by tunnel junctions, a two dimension model is built. By using the finite difference method, the current density and carriers within the device can be obtained. According to the simulation results, there exists a severe current spreading for the novel device, so we proposed a double-side strip structure to confine the carriers along the lateral direction. Experimental result shows that for a 4-active region laser combined with the double-side strip structure, the slop efficiency is as high as 2.97W/A, and an output power of 4.44W can be reached at 2A.