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Articles 1 - 9 of 9
Full-Text Articles in Physics
Global Association Of Aerosol With Flash Density Of Intense Lightning, Orit Altaratz, Beata Kucienska, Alexander Kostinski, Graciela B. Raga, Ilan Koren
Global Association Of Aerosol With Flash Density Of Intense Lightning, Orit Altaratz, Beata Kucienska, Alexander Kostinski, Graciela B. Raga, Ilan Koren
Department of Physics Publications
A global scale study of the association between aerosol loading and lightning production was conducted, using a full year’s data for 2012 (as well as seasonal data) of the cloud-to-ground lightning record from the world wide lightning location network and aerosol optical depth measured by MODIS. 70% of all grid squares examined and 94% of the statistically significant ones had higher flash densities under polluted conditions than the clean ones. This trend is evident for large continental regions in North, Central and South America, Europe, southern Africa and north-east Australia. A detailed examination of the link to the meteorology was …
Robustness And Mode Selectivity In Parity-Time (Pt) Symmetric Lasers, M. H. Teimourpour, M. Khajavikhan, Demetrios N. Christodoulides, Ramy El-Ganainy
Robustness And Mode Selectivity In Parity-Time (Pt) Symmetric Lasers, M. H. Teimourpour, M. Khajavikhan, Demetrios N. Christodoulides, Ramy El-Ganainy
Department of Physics Publications
We investigate two important aspects of PT symmetric photonic molecule lasers, namely the robustness of their single longitudinal mode operation against instabilities triggered by spectral hole burning effects, and the possibility of more versatile mode selectivity. Our results, supported by numerically integrating the nonlinear rate equations and performing linear stability analysis, reveals the following: (1) In principle a second threshold exists after which single mode operation becomes unstable, signaling multimode oscillatory dynamics, (2) For a wide range of design parameters, single mode operation of PT lasers having relatively large free spectral range (FSR) can be robust even at higher gain …
Cloud Droplets To Drizzle: Contribution Of Transition Drops To Microphysical And Optical Properties Of Marine Stratocumulus Clouds, S Glienke, A. Kostinski, J P. Fugal, R. A. Shaw, S Borrmann, J Stith
Cloud Droplets To Drizzle: Contribution Of Transition Drops To Microphysical And Optical Properties Of Marine Stratocumulus Clouds, S Glienke, A. Kostinski, J P. Fugal, R. A. Shaw, S Borrmann, J Stith
Department of Physics Publications
Aircraft measurements of the ubiquitous marine stratocumulus cloud type, with over 3000 km of in situ data from the Pacific during the Cloud System Evolution in the Trades experiment, show the ability of the Holographic Detector for Clouds (HOLODEC) instrument to smoothly interpolate the small and large droplet data collected with Cloud Droplet Probe and 2DC instruments. The combined, comprehensive instrument suite reveals a surprisingly large contribution in the predrizzle size range of 40–80 μm (transition droplets, or drizzlets), a range typically not measured and assumed to reside in a condensation‐to‐collision minimum between cloud droplet and drizzle modes. Besides shedding …
Two-Dimensional Electronics And Optoelectronics: Present And Future, Zhixian Zhou, Yoke Khin Yap
Two-Dimensional Electronics And Optoelectronics: Present And Future, Zhixian Zhou, Yoke Khin Yap
Department of Physics Publications
Since the successful isolation of graphene a little over a decade ago, a wide variety of two-dimensional (2D) layered materials have been studied. They cover a broad spectrum of electronic properties, including metals, semimetals, semiconductors, and insulators. Many of these 2D materials have demonstrated promising potential for electronic and optoelectronic applications.
Non-Hermitian Matter-Wave Mixing In Bose-Einstein Condensates: Dissipation-Induced Amplification, S. Wuster, Ramy El-Ganainy
Non-Hermitian Matter-Wave Mixing In Bose-Einstein Condensates: Dissipation-Induced Amplification, S. Wuster, Ramy El-Ganainy
Department of Physics Publications
We investigate the nonlinear scattering dynamics in interacting atomic Bose-Einstein condensates under non-Hermitian dissipative conditions. We show that, by carefully engineering a momentum-dependent atomic loss profile, one can achieve matter-wave amplification through four-wave mixing in a quasi-one-dimensional nearly-free-space setup—a process that is forbidden in the counterpart Hermitian systems due to energy mismatch. Additionally, we show that similar effects lead to rich nonlinear dynamics in higher dimensions. Finally, we propose a physical realization for selectively tailoring the momentum-dependent atomic dissipation. Our strategy is based on a two-step process: (i) exciting atoms to narrow Rydberg or metastable excited states, and (ii) introducing …
Recent Advances In Electronic And Optoelectronic Devices Based On Two-Dimensional Transition Metal Dichalcogenides, Mingxiao Ye, Dongyan Zhang, Yoke Khin Yap
Recent Advances In Electronic And Optoelectronic Devices Based On Two-Dimensional Transition Metal Dichalcogenides, Mingxiao Ye, Dongyan Zhang, Yoke Khin Yap
Department of Physics Publications
Two-dimensional transition metal dichalcogenides (2D TMDCs) offer several attractive features for use in next-generation electronic and optoelectronic devices. Device applications of TMDCs have gained much research interest, and significant advancement has been recorded. In this review, the overall research advancement in electronic and optoelectronic devices based on TMDCs are summarized and discussed. In particular, we focus on evaluating field effect transistors (FETs), photovoltaic cells, light-emitting diodes (LEDs), photodetectors, lasers, and integrated circuits (ICs) using TMDCs.
Terrestrial Glint Seen From Deep Space: Oriented Ice Crystals Detected From The Lagrangian Point, Alexander Marshak, Tamas Varnai, Alexander Kostinski
Terrestrial Glint Seen From Deep Space: Oriented Ice Crystals Detected From The Lagrangian Point, Alexander Marshak, Tamas Varnai, Alexander Kostinski
Department of Physics Publications
The Deep Space Climate Observatory (DSCOVR) spacecraft resides at the first Lagrangian point about one million miles from Earth. A polychromatic imaging camera onboard delivers nearly hourly observations of the entire sunlit face of the Earth. Many images contain unexpected bright flashes of light over both ocean and land. We construct a yearlong time series of flash latitudes, scattering angles, and oxygen absorption to demonstrate conclusively that the flashes over land are specular reflections off tiny ice platelets floating in the air nearly horizontally. Such deep space detection of tropospheric ice can be used to constrain the likelihood of oriented …
Topological Tight-Binding Models From Nontrivial Square Roots, J. Arkinstall, M. H. Teimourpour, L. Feng, Ramy El-Ganainy, H. Schomerus
Topological Tight-Binding Models From Nontrivial Square Roots, J. Arkinstall, M. H. Teimourpour, L. Feng, Ramy El-Ganainy, H. Schomerus
Department of Physics Publications
We describe a versatile mechanism that provides tight-binding models with an enriched, topologically nontrivial band structure. The mechanism is algebraic in nature, and leads to tight-binding models that can be interpreted as a nontrivial square root of a parent lattice Hamiltonian—in analogy to the passage from a Klein-Gordon equation to a Dirac equation. In the tight-binding setting, the square-root operation admits to induce spectral symmetries at the expense of broken crystal symmetries. As we illustrate in detail for a simple one-dimensional example, the emergent and inherited spectral symmetries equip the energy gaps with independent topological quantum numbers that control the …
Non-Hermitian Engineering Of Synthetic Saturable Absorbers For Applications In Photonics, M. H. Teimourpour, A. Rahman, K. Srinivasan, Ramy El-Ganainy
Non-Hermitian Engineering Of Synthetic Saturable Absorbers For Applications In Photonics, M. H. Teimourpour, A. Rahman, K. Srinivasan, Ramy El-Ganainy
Department of Physics Publications
We explore a type of synthetic saturable absorber based on quantum-inspired photonic arrays. We demonstrate that the interplay between optical Kerr nonlinearity, interference effects, and non-Hermiticity through radiation loss leads to a nonlinear optical filtering response with two distinct regimes of small and large optical transmissions. More interestingly, we show that the boundary between these two regimes can be very sharp. The threshold optical intensity that marks this abrupt “phase transition” and its steepness can be engineered by varying the number of the guiding elements. The practical feasibility of these structures as well as their potential applications in laser systems …