Systematic Study of the Effects of Modulation p-Doping on 1.3-$\mu{\hbox {m}}$ Quantum-Dot Lasers

The effects of modulation p-doping on 1.3- $\mu{\hbox {m}}$ InGaAs–InAs quantum-dot (QD) lasers are systematically investigated using a series of wafers with doping levels from 0 to 18 acceptors per QD. Various characterization techniques for both laser diodes and surface-emitting light-emitting diode structures are employed. We report: 1) how the level of modulation p-doping alters the length dependant laser characteristics (in turn providing insight on various key parameters); 2) the effect of modulation p-doping on the temperature dependence of a number of factors and its role in obtaining an infinite ${\rm T} _{0}$; 3) how increasing concentrations of modulation p-doping affects the saturated gain, differential gain, and gain profile of the lasers; and finally, 4) the effect modulation p-doping has on the small signal modulation properties of 1.3-$\mu{\hbox {m}}$ QD lasers. In each of these areas, the role of modulation p-doping is established and critically discussed.