High-performance 1.06-μm InGaAs/GaAs double-quantum-well semiconductor lasers with asymmetric heterostructure layers

High-performance 1.06-μm InGaAs/GaAs double-quantum-well (DQW) asymmetric herero- structure semiconductor lasers have been designed, fabricated and characterized. The laser structure, grown by metal-organic chemical vapor deposition (MOCVD), mainly consists of compositionally graded p-Al_xGa_1−xAs upper cladding layers, a p-Al_xGa_1−xAs upper waveguide layer, a 1.06-μm InGaAs/GaAs DQW active region, an un-doped In_1−xGa_xAs_yP_1−y lower waveguide layer, and compositionally graded n-doped In_1−xGa_xAs_yP_1−y lower cladding layers. Measurement results of the as-cleaved ridge waveguide (RWG) lasers with a contact ridge width of 25 μm and different cavity lengths (900 to 2765 μm) demonstrated state-of-the-art performances with a high internal quantum efficiency (η _i) of ∼98.4% and a low internal optical loss (α _i) of ∼1.01 cm⁻¹ at 20 °C. The laser has demonstrated high characteristic temperatures of 245 K (T ₀) and 663 K (T ₁) from 20 to 50 °C, and the cavity length dependent behaviour of T ₀ and T ₁ has also been investigated from 20 to 80 °C. Furthermore, a low transparency current density (J _tr) of 77 A/cm²/QW in this laser structure is obtained at 20 °C, which is among one of the lowest values reported so far for 1.06-μm InGaAs/GaAs semiconductor lasers. (paper)