Fabry-Perot lasers: Temperature and many-body effects

We have demonstrated the integration of advanced gain modeling based on a microscopic many-body theory into full-scale laser simulations. Our approach has been applied to the investigation of the temperature sensitivity of InGaAsP quantum well lasers. It has been shown that the gain broadening due to carrier-carrier and carrier-phonon scattering-induced dephasing dominantly determines the temperature sensitivity of these laser structures rather than nonradiative recombination.Our microscopic gain model allows for an accurate prediction of the gain spectrum for a specific material system based solely on material parameters. The energetic position and the collision broadening of the gain maximum have a significant impact on the optical properties of Fabry-Perot laser diodes, in particular, emission wavelength, threshold current, and slope efficiency, as discussed here. The detailed spectral behavior of the gain can be expected to be of more importance for advanced structures like VCSELs, which exhibit a strong optical confinement in the longitudinal direction. The advanced many-body gain theory has been compared with the freecarrier gain model, which is a common approach in commercial laser simulators. The advantage of the predictive modeling of the gain by the microscopic many-body theory with respect to simpler models carries over to the full-scalelaser simulation. Calibration effort can be reduced while improving the overall predictive capabilities of the simulation. In order to improve the free-carrier approach, density, temperature, and energy dependences would have to be added to the gain broadening model to describe effects of carrier-carrier and carrier-phonon scattering phenomenologically. We suggest a calibration procedure that determines the gain model parameters first by performing optical experiments in order to avoid ambiguities between transport and gain models in describing temperature and density dependence of the overall laser performance. Using the microscopic many-body theory, this additional ca libration step can be avoided.