Temperature Sensitivity Dependence on Cavity Length in p-Type Doped and Undoped 1.3-$\mu$ m InAs–GaAs Quantum-Dot Lasers

We have fabricated 1.3-mum InAs-GaAs quantum-dot (QD) lasers with and without p-type modulation doping and their characteristics have been investigated. We find that introducing p-type doping in active regions can improve the temperature stability of 1.3-mum InAs-GaAs QD lasers, but it does not increase the saturation modal gain of the QD lasers. The saturation modal gain obtained from the two types of lasers is identical (17.5 cm
^-1
). Moreover, the characteristic temperature increases as cavity length increases for the two types of lasers, and it improves more significantly for the lasers with p-type doping due to their higher gain.