Dependence of the injection current at lasing threshold on structure and losses in AlGaN/GaN lasers

We present calculations of the threshold current densities, /th, in AIGaN/GaN double heterostructure lasers for different active region thickness, losses, and cavity lengths. Two-dimensional (2-D) numerical simulations indicate that for a 100-μm long cavity, a 0.1-μm thick active region gives the lowest /th when only mirror losses are present. As losses increase, the minimum moves to thicker active regions. /th versus optical loss plots demonstrate that with the high optical losses in the materials grown, it will be easier to induce lasing in thick active region structures. Results for AIGaAs/GaAs lasers presented for comparison, demonstrate that AIGaN/GaN lasers have higher J_th unless the active region is very thin.