Carrier Dynamics in Quantum Well Lasers

Abstract

A fully microscopic theory is used to perform an analysis of carrier-carrier and carrier-LO phonon scattering in semiconductor quantum wells, focussing on the high-density case relevant for laser structures. A large variance of scattering times is observed depending on the material parameters, apparently contradicting popular belief in some cases. For instance, carrier-carrier scattering may slow down when the carrier density is increased. Electron-hole scattering times are found to be on the same order of magnitude as carrier-phonon scattering, making the introduction of a separate electron and hole temperature necessary. Heating by optical pumping is investigated and plasma cooling is shown to be possible by optical pumping of the laser structure.

Microscopic simulation of nonequilibrium features in quantum-well pumped semiconductor disk lasers

“…This represents the lower edge of reported carrier-phonon relaxation times c-p . 15 Comparative simulations with a relaxation time of 5 ps reveal generally the same but more pronounced nonequilibrium effects ͑not shown͒. Due to the plasma scattering between the electrons and holes, a band dependent relaxation time with c-p e c-p h is expected to lead to similar results.…”

“…Carrier-carrier as well as carrier-phonon scattering processes are included by a scattering rate approach 12,13 with microscopically determined scattering rates. 14,15 The carrier losses due to spontaneous emission and Auger processes are calculated microscopically, 16,17 while the probe specific monomolecular loss rate is assumed to be 10 7 s −1 . 18 Using microscopically motivated carrier temperature and density dependent polarization dephasing times, we can calculate the absorption spectrum of the quantum wells for different equilibrium carrier distributions.…”

High average output power from a backside-cooled 2-µm InGaSb VECSEL with full gain characterization

“…To date, for 2-µm VECSEL, the understanding of the gain parameters heavily relies on simulations. These simulations often give limited insight since they focus on quantum structures or an isolated quantum well (QW) and therefore often ignore micro-resonator effects, temperature gradients or the integration of the QW that can potentially change the gain [24][25][26][27][28][29].…”