Performance of InGaN based blue laser diodes (LDs) with different In content of (In)GaN lower waveguide (LWG) layers are investigated by simulation and experimental methods. It is found from the simulation results that the threshold current decreases and slope efficiency increases when the In content of InGaN LWG layer increases from 0% to 6%. However, when the In content is too high, the optical confinement factor of MQWs decreases, recombination rate in LWG layer increases and the surface morphology becomes roughness, all of these result in the deterioration of the performance of LDs with high In content InGaN LWG layer, the output power decreases from 97 to 83 mW at the injection current of 100 mA. It agrees well with the experiment results that the performance of LDs can be improved by using a low In content InGaN instead of GaN as lower waveguide layer.
