Multi-dimensional modeling and simulation of semiconductor nanophotonic devices

Self-consistent modeling and multi-dimensional simulation of semiconductor nanophotonic devices is an important tool in the development of future integrated light sources and quantum devices. Simulations can guide important technological decisions by revealing performance bottlenecks in new device concepts, contribute to their understanding and help to theoretically explore their optimization potential. The efficient implementation of multi-dimensional numerical simulations for computer-aided design tasks requires sophisticated numerical methods and modeling techniques. We review recent advances in device-scale modeling of quantum dot based single-photon sources and laser diodes by self-consistently coupling the optical Maxwell equations with semiclassical carrier transport models using semi-classical and fully quantum mechanical descriptions of the optically active region, respectively. For the simulation of realistic devices with complex, multi-dimensional geometries, we have developed a novel hp-adaptive finite element approach for the optical Maxwell equations, using mixed meshes adapted to the multi-scale properties of the photonic structures. For electrically driven devices, we introduced novel discretization and parameter-embedding techniques to solve the drift-diffusion system for strongly degenerate semiconductors at cryogenic temperature. Our methodical advances are demonstrated on various applications, including vertical-cavity surface-emitting lasers, grating couplers and single-photon sources

Empathic Stress in Stranger Dyads: Examining the Role of Oxytocin and Testosterone Release after the Manipulation of the Observer’s Empathic Involvement

Psychosocial stress does not only affect individuals directly. The mere observation of a stressed target can also elicit a full-blown stress response in the observing individual. This so-called empathic stress includes two types: resonant and vicarious stress. In stress resonance, the observer shows a stress response, which is proportional to the target’s stress response. Conversely, vicarious stress evolves independently of the target’s actual stress response and is rather a projection of the observer’s own perspective onto the stressful situation. Given the immense importance of chronic stress in the development of stress-associated diseases (Chrousos, 2009; Herman, 2022), empathic stress may represent a health risk, especially in individuals who are frequently confronted with other’s stress. To date, not much is known about the biophysiological mechanisms of empathic stress between strangers (Engert et al., 2019). Therefore, in the current study, we assessed oxytocin and testosterone in observers, while they were watching an unknown target undergoing the Trier Social Stress Test (TSST; Kirschbaum et al., 1993). Further, we experimentally manipulated environmental factors for observers or, more precisely, their empathic involvement with the target. To facilitate relating to the target’s state, and thus induce a more empathic stance, observers were themselves exposed to the TSST approximately one week before observing the target in the TSST (empathy group). To create distance to the target’s stressful state, and induce a perspective of power, observers were asked to determine the target’s financial compensation based on their performance in the TSST (power group). Additionally, a control group without any manipulation was tested

Network Analysis of Enzyme Activities and Metabolite Levels and Their Relationship to Biomass in a Large Panel of Arabidopsis Accessions[C][W][OA]

This work uses natural genetic diversity to study species-wide connectivity between metabolites, enzymes, and biomass. The resulting network analysis, based on 129 Arabidopsis accessions, shows that biomass can be predicted by two independent integrative metabolic biomarkers: preferential investment in photosynthetic machinery and optimization of carbon use

Multi-dimensional Modeling and Simulation of Semiconductor Nanophotonic Devices

Self-consistent modeling and multi-dimensional simulation of semiconductor nanophotonic devices is an important tool in the development of future integrated light sources and quantum devices. Simulations can guide important technological decisions by revealing performance bottlenecks in new device concepts, contribute to their understanding and help to theoretically explore their optimization potential. The efficient implementation of multi-dimensional numerical simulations for computer-aided design tasks requires sophisticated numerical methods and modeling techniques. We review recent advances in device-scale modeling of quantum dot based single-photon sources and laser diodes by self-consistently coupling the optical Maxwell equations with semi-classical carrier transport models using semi-classical and fully quantum mechanical descriptions of the optically active region, respectively. For the simulation of realistic devices with complex, multi-dimensional geometries, we have developed a novel hp-adaptive finite element approach for the optical Maxwell equations, using mixed meshes adapted to the multi-scale properties of the photonic structures. For electrically driven devices, we introduced novel discretization and parameter-embedding techniques to solve the drift-diffusion system for strongly degenerate semiconductors at cryogenic temperatures. Our methodical advances are demonstrated on various applications, including vertical-cavity surface-emitting lasers, grating couplers and single-photon sources