Dissertation Defense: Sam McLaren, "Multidimensional microscopic modeling of nonequilibrium carrier dynamics within vertical external-cavity surface-emitting lasers"

    Thursday, July 29, 2021 - 10:00am

    Topic: Sam McLaren's Dissertation Defense
    Time: July 29, 2021 10:00 AM Arizona
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    Mode-locked vertical external-cavity surface emitting lasers are promising compact sources for high-power, ultrafast pulses with excellent beam quality and the flexibility offered by an external cavity. Typical models of these lasers use macroscopic or quasi-static approaches based on rate or delay differential equations. Although these approaches have shown widespread success, they often require numerous experimentally tuned parameters and do not capture the ultrafast nonequilibrium dynamics present as the field interacts with the quantum well. The Maxwell Semiconductor Bloch Equations has reduced parametrization and captures the carrier dynamics by coupling together a numerical wave propagator to a first principles quantum mechanical description of the induced microscopic polarization within the active semiconductor quantum well. This gives a detailed view into the ultrafast nonequilibrium charge carrier dynamics where carriers are driven far from Fermi distributions and allows the predictive design of future VECSEL devices. Previous work utilizing this model has been restricted to a single longitudinal dimension and linearly oriented cavities. In this thesis, the model is expanded to include transverse effects as well as to model cavities exhibiting non-normal incidence on the semiconductor heterostructures within it. The former is done through the coupling of single-dimensional models using a pseudospectral wave propagator. The latter is done through a reference frame transform in conjunction with an expansion of the Semiconductor Bloch Equations. Optimal cavity conditions for achieving modelocking within a variety of standard, as well as unconventional, VECSEL cavities are explored and characterized as they are driven by the underlying nonequilbrium carrier dynamics.