InGaAs/GaAs 0.98- $\mu{\hbox {m}}$ Low-Divergence Central-Lobe Semiconductor Lasers With $\delta$ -Doped Resonant Tunneling Quantum Wells

In this paper, we describe a new structure design for producing low-threshold, high-efficiency, and high-brightness 0.98-$\mu{\hbox {m}}$ lasers. In this structure, we incorporated a self-discriminating weak optical confinement asymmetrical waveguide coupled to passive waveguides, and an active region based on three InGaAs quantum wells (QWs) coupled to Te n-type $\delta$-doping. Optimized coupling between the $\delta$-doping and the three QWs, together with waveguide optimization and doping profile optimization, yields $J_{\rm th}=98\ {\hbox {A/cm}}^{2}$ per QW, ${T}_{0}=80\;^{\circ}\hbox{C}$, and a far-field central lobe angle of $\sim 10^{\circ}$.