Optimization of THz semi-insulating surface plasmon waveguide structures of GaSb/AlSb quantum cascade lasers

摘要

We designed and analyzed the semi-insulating surface plasmon waveguide structures of GaSbbased quantum cascade lasers (QCLs) operating in the terahertz (THz) region of 2. 6-6. 5 THz using the finite element method. For improving the guiding property of THz QCL waveguide structures, a low threshold gain (g _(th)) and a high optical confinement (Γ) could be achieved by optimizing the doping concentration and the thickness of plasma layer, the waveguide width, the substrate thickness, and the number of stages in active core region at various operating frequencies (2. 6-6. 5 THz). The effect of different substrates on the g _(th) and Γ of THz QCL waveguide structures was also investigated.