Silicon photonics is a key technology needed to ensure the required increase in data center energy efficiency and performance over the next decade. Such a driving technology is necessary to manage the rapidly increasing demand in data centers and prevent a massive increase in their energy consumption. A promising approach to bridge the gap from electronics to optics is the growth of monolithically integrated III-V nanowire lasers on silicon. However, with few exceptions, these nanowire lasers are currently only optically pumped. To realize in the future an electrically pumped nanowire laser on silicon and exploit their full potential, a detailed understanding of ultrafast carrier dynamics and photon carrier thermal processes that occur during the laser operation is needed. In this thesis, we developed a comprehensive numerical model of the laser dynamics in bulk GaAs nanowires. These simulations provide access to the microscopic interactions of the internal laser processes and their non-equilibrium dynamics during optical excitation. We describe in detail the different numerical aspects and models for the model implementation. The numerical simulations were compared with measurements performed on bulk GaAs nanowire lasers under optically pumped continuous wave excitation. We observe a good agreement of the simulation with the measurements in all extracted laser quantities, such as the power-dependent carrier density, output intensity, carrier temperature, bandgap renormalization, shift of the lasing peak energy, and linewidth narrowing. The quantum statistical model showed a strong thermal non-equilibrium of the electron-hole plasma above the laser threshold. This causes a further increase in carrier density and carrier temperature, a shift in the lasing peak energy, a renormalization of the bandgap, and prevent finally a gain clamping of the laser. The absence of a linewidth narrowing in bulk GaAs nanowire lasers could also be described very accurately using the quantum statistical model. Furthermore, we showed that a rate equation approach with a gain saturation model can reproduce the behavior of the charge carrier density and the output power with similar accuracy. However, this simplified approach is not suitable for a description of the linewidth behavior. Subsequently, the quantum statistical model was used to study the temporal laser dynamics of GaAs nanowire lasers subjected to pulsed excitation. We have demonstrated that the sensitive interaction of the individual recombination and scattering processes can lead to oscillations of the output intensity. These oscillations result from a periodic redistribution of the charge carriers within their bands. Furthermore, these numerical simulations were compared with pump-probe measurements on bulk GaAs nanowire lasers. In the measurements, the oscillations of the laser field amplitude and phase can reach frequencies of several hundred GHz. We compared the behavior of the oscillation frequency and the laser turn-on time with the simulation results as a function of the excitation power and the lattice temperature. Again, we observed an excellent agreement of the quantum statistical model with the pump-probe experiments over almost the entire measurement range. The comprehensive numerical simulations on GaAs based nanowire lasers enabled a fundamental understanding of the individual microscopic laser processes and their respective delicate interaction. With these detailed investigations, we were able to demonstrate the superior properties and full potential of monolithically integrated nanowire lasers. Therefore, this thesis build an important foundation for the future development of highly integrated nanoscale light sources on silicon.weiterlesen