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/sub 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-/spl mu/m long cavity, a 0.1-/spl mu/m thick active region gives the lowest J/sub th/ when only mirror losses are present. As losses increase, the minimum moves to thicker active regions. J/sub 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/sub th/ unless the active region is very thin.