Epitaxially stacked lasers with Esaki junctions: A bipolar cascade laser

We present a two-color (956 and 985 nm) InGaAs/AlGaAs laser structure epitaxially stacked through a low-resistance ${\text{(10}}^{\text{−5}}{\text{–10}}^{\text{−4}}\mathrm{\hspace{0.17em}\Omega \hspace{0.17em}}{\mathrm{cm}}^{\mathrm{2}})$ Esaki junction, exhibiting two threshold characteristics. It is shown that this structure can be considered as a bipolar cascade laser.