In this paper, a design for a high extinction ratio Mach-Zehnder optical modulator is proposed. The switchable refractive index of the germanium-antimony-selenium-tellurium (GSST) phase change material is employed to induce destructive interference between the waves passing through Mach-Zehnder interferometer (MZI) arms and to realize amplitude modulation. A novel, to the best of our knowledge, asymmetric input splitter is designed for the MZI to compensate for unwanted amplitude differences between MZI arms and increase the modulator performance. Three-dimensional finite-difference-time-domain simulations show a very high extinction ratio (ER) and low insertion loss (IL) of 45 and 2 dB, respectively, for the designed modulator at the wavelength of 1550 nm. Moreover, the ER is above 22 dB, and the IL is below 3.5 dB in the wavelength range of 1500-1600 nm. The thermal excitation process of GSST is also simulated using the finite-element method, and the speed and energy consumption of the modulator are estimated.
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Environ Sci Technol
December 2024
Climate and Environmental Physics, Physics Institute, and Oeschger Centre for Climate Change Research, University of Bern, Sidlerstrasse 5, Bern 3012, Switzerland.
This study presents the integration of the single-particle extinction and scattering (SPES) method in a continuous flow analysis (CFA) setup. Continuous measurements with the instrument allow for the characterization of water-insoluble particles in ice cores at high resolution with a minimized risk of contamination. The SPES method can be used to investigate particles smaller than 1 μm, which previously could not be detected by instruments typically used in CFA.
View Article and Find Full Text PDFNat Ecol Evol
December 2024
IBE, Institute of Evolutionary Biology (UPF-CSIC), Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain.
Ecological variation and anthropogenic landscape modification have had key roles in the diversification and extinction of mammals in Madagascar. Lemurs represent a radiation with more than 100 species, constituting roughly one-fifth of the primate order. Almost all species of lemurs are threatened with extinction, but little is known about their genetic diversity and demographic history.
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December 2024
U.S. Bureau of Reclamation Bay-Delta Office, 801 I St., Suite 140, Sacramento, CA 95814, USA.
Freshwater fishes are increasingly facing extinction. Some species will require conservation intervention such as habitat restoration and/or population supplementation through mass-release of hatchery fish. In California, USA, a number of conservation strategies are underway to increase abundance of the endangered Delta Smelt (); however, it is unclear how different estuarine conditions influence hatchery fish.
View Article and Find Full Text PDFTheor Popul Biol
December 2024
Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver B.C., Canada, V6T 1Z2; Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver B.C., Canada, V6T 1Z4.
Phages use bacterial host resources to replicate, intrinsically linking phage and host survival. To understand phage dynamics, it is essential to understand phage-host ecology. A key step in this ecology is infection of bacterial hosts.
View Article and Find Full Text PDFNanotechnology
December 2024
Department of Physics, King Faisal University, King Faisal University P.O. 380 Ahsaa 31982, Al Ahsa, 31982, SAUDI ARABIA.
An anisotropic plasmonic trimer is proposed as an effective spectroscopic amplifier for the maximum signal enhancement of the Hyper-Raman Scattering (HRS) process. The three-particle system is composed of asymmetric Au nanorings arranged collinearly in a J-aggregate configuration and illuminated by a longitudinally polarized light. The optical properties of the considered trimer have been numerically simulated by the Finite-Difference Time-Domain (FDTD) method.
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