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

We present calculations of the threshold current densities, J_th, in AlGaN/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 J_th when only mirror losses are present. As losses increase, the minimum moves to thicker active regions. J_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 AlGaAs/GaAs lasers presented for comparison, demonstrate that AlGaN/GaN lasers have higher J_th unless the active region is very thin