Date: Thursday, November 20, 2025

Time: 12:30 PM to 1:45 PM

Location:  PAIS, Room 2540 and Zoom

Speaker:Professor Jerome V Moloney of Wyant College of Optical Sciences and Department of Mathematics at the University of Arizona, Tucson 85721

Abstract:

The discovery and development of semiconductor lasers rapidly followed Maiman’s discovery of the laser in the 1960’s with the technology growing so rapidly that attempts to establish a rigorous theoretical foundation lagged far behind. Parameterized models of optical gain and loss became the norm and although based on sound physical principles they lacked a proper description of what after all of what essentially were nontrivial many body interactions within and between electron and hole plasmas. The seminal work of Haug and Koch with many follow-on theoretical developments, set the stage for a fully predictive first principles microscopic theory that provided the first quantitative agreement with experimental measurement of laser gain, photoluminescence and Auger losses. The many-body theory encapsulated by Maxwell- Semiconductor Bloch equations (MSBE), represent the leading order terms in an infinite hierarchy that, when appropriately truncated, provide a powerful semiconductor epitaxy design tool that has been transitioned into a commercial software package.

In this talk, I will describe how a systematic inclusion of Hartree-Fock field and energy renormalization terms together with higher order correlations, account for all microscopic processes involved on light-semiconductor interactions. The theory will be shown to provide a one-to-one agreement with gain measurements across many classes of semiconductor quantum well materials and establishes the limitations of the famous ABC laws that phenomenologically account respectively for defect, spontaneous emission radiative and Auger losses. My talk will include examples of experiments on a broad class semiconductor disk lasers where the microscopic theory was used to design a host of novel CW and mode-locked laser sources with applications to compact extreme UV, room temperature tunable THz, artificial Guidestar, offset=free mid-IR frequency comb and angle tunable multi-wavelength sources.

Recently, the theory was extended to a novel class of quasi-2D Transition Metal Dichalcogenide (TMDC) materials that exhibit huge hundreds of meV bandgap renormalization and have prominent room temperature excitonic features. A monolayer of this material exhibits a finite bandgap in the visible and an indirect gap for dual or multilayers. In contrast to graphene which exhibits a zero energy band gap, these materials have been shown to lase in the visible. These novel materials are proposed as wearable sensors, in spintronics, solar cells, as photodetectors etc. Recent high field physics applications include many-body enhancement of high harmonic generation in these materials with plans to extend to topologically nontrivial materials.

Biography: