Optimization of quantum well structure for GaAs/AlGaAs ring lasers

In order to study effect of multiple quantum well (MQW) on threshold current of a semiconductor ring laser (SRL), the function relationship between threshold current of SRL and MQW structural parameters was analyzed based on the oscillation condition of a conventional Fabry-Perot laser. An optimal expression of quantum well number was derived. Equivalent model of SRL was founded by utilizing device simulation software ATLAS. The effect of quantum well number, well width and barrier thickness on threshold current density of SRL were simulated and analyzed at various operating temperatures. The simulation results show that threshold current decreases firstly and then increases with increasing of well number and well width. A set of optimal values existed. After determining the appropriate well number and well width, the barrier with relatively narrower thickness can further reduce the threshold current. For GaAs/AlGaAs material system and device structure, the optimal parameters are M=3, dw=20nm, and db=10nm respectively.