Publications related to Group velocity

The dynamics of unsteady frictional slip pulses

Self-healing slip pulses are major spatiotemporal failure modes of frictional systems, featuring a characteristic size L(t) and a propagation velocity c(p)(t) (t is time). Here, we develop a theory of slip pulses in realistic rate- and state-dependent fric ...

National Academy of Sciences2023

Spin wave dispersion of ultra-low damping hematite (α-Fe2O3) at GHz frequencies

Dirk Grundler, Mohammad Hamdi, Ferdinand Rémy Hynek Posva

Raw data associated to the manuscript ‘’Spin wave dispersion of ultra-low damping hematite (α-Fe2O3) at GHz frequencies‘’, Physical Review Materials 7, 054407(2023); doi: 10.1103/PhysRevMaterials.7.054407 Information about file fo ...

Zenodo2023

Spin wave dispersion of ultra-low damping hematite ( α−Fe2O3 ) at GHz frequencies

Dirk Grundler, Mohammad Hamdi, Ferdinand Rémy Hynek Posva

Low magnetic damping and high group velocity of spin waves (SWs) or magnons are two crucial parameters for functional magnonic devices. Magnonics research on signal processing and wave-based computation at GHz frequencies focused on the artificial ferrimag ...

2023

Space-time wave packets with reduced divergence and tunable group velocity generated in free space after multi-mode fiber propagation

Tobias Kippenberg, Maxim Karpov, Hao Song, Xinzhou Su

Previously, space-time wave packets (STWPs) have been gen-erated in free space with reduced diffraction and a tunable group velocity by combining multiple frequency comb lines each carrying a single Bessel mode with a unique wave num-ber. It might be poten ...

Optica Publishing Group2023

Ultra-broadband terahertz radiation by supercontinuum generation and optical rectification in a dispersion-engineered waveguide: a numerical study

Ileana-Cristina Benea-Chelmus, Aleksei Gaier

In this work, we propose a numerical approach based on forward coupled mode modeling to simultaneously evaluate second- and third-order nonlinearities inside a dispersion-engineered waveguide towards the goal of generating broadband terahertz (THz) radiati ...

IEEE2023

Reconfigurable nonreciprocal excitation of propagating exchange spin waves in perpendicularly magnetized yttrium iron garnet thin films

Jean-Philippe Ansermet, Haiming Yu, Yu Zhang, Peng Chen, Jilei Chen, Tao Liu, Jinlong Wang, Rundong Yuan

We report the nonreciprocal excitation of propagating forward volume exchange spin waves in yttrium iron garnet (YIG) thin film with perpendicular anisotropy by bringing the in-plane magnetization of Co20Fe60B20 (CoFeB) nanowires to resonance. All-electric ...

Amer Physical Soc2023

Low-Loss Anisotropic Image Polaritons in van der Waals Crystal alpha-MoO3

Sergejs Boroviks

Orthorhombic molybdenum trioxide (alpha-MoO3), a newly discovered polaritonic van der Waals crystal, is attracting significant attention due to its strongly anisotropic mid-infrared phonon-polaritons. At the same time, coupling of polariton with its mirror ...

WILEY-V C H VERLAG GMBH2022

Lack of Out-of-Plane Dispersion of the Magnetic Excitations of Charge-Stripe Ordered La2−xSrxNiO4+δ

Paul Gregory Freeman, Alexandra Angeline Turrini

The dependence of the magnetic excitations in the out-of-NiO-plane direction of charge stripe ordered La2-xSrxNiO4+delta x = 0.3 and delta = 0.11 +/- 0.01 were investigated by inelastic neutron scattering. No dispersion was observed for the magnetic excita ...

Physical Soc Japan2022

Zero dispersion Kerr solitons in optical microresonators

Tobias Kippenberg, Junqiu Liu, Wenle Weng, Miles Henry Anderson, Alexey Tikan

Solitons are shape preserving waveforms that are ubiquitous across nonlinear dynamical systems from BEC to hydrodynamics, and fall into two separate classes: bright solitons existing in anomalous group velocity dispersion, and switching waves forming 'dark ...

Nature Research2022

Fiber Buckling in Confined Viscous Flows: An Absolute Instability Described by the Linear Ginzburg-Landau Equation

François Gallaire, Jean Cappello

We explore the dynamics of a flexible fiber transported by a viscous flow in a Hele-Shaw cell of height comparable to the fiber height. We show that long fibers aligned with the flow experience a buckling instability. Competition between viscous and elasti ...

AMER PHYSICAL SOC2022

Platicon microcomb generation using laser self-injection locking

Tobias Kippenberg, Rui Ning Wang, Junqiu Liu, Wenle Weng, Jijun He, Yang Liu, Miles Henry Anderson

The past decade has witnessed major advances in the development and system-level applications of photonic integrated microcombs, that are coherent, broadband optical frequency combs with repetition rates in the millimeter-wave to terahertz domain. Most of ...

Nature Portfolio2022

Generation of Optical Frequency Combs in an Optical Microresonator Pumped by a 780-nm Laser Diode in Self-Injection Locking Regime

Andrey Voloshin

Experimental data for the generation of optical frequency combs in magnesium fluoride microcavities with whispering gallery modes at 780 nm are presented. This wavelength corresponds to the normal group velocity dispersion for pumping by a laser diode oper ...

2022

Complementary Metasurfaces for Guiding Electromagnetic Wave

Mohammad Sajjad Mirmoosa

Metasurfaces can be employed for designing waveguides that confine the electromagnetic energy while they are open structures. In this communication, we introduce a new type of such waveguides, formed by two penetrable metasurfaces having complementary isot ...

2021

Long decay length of magnon-polarons in BiFeO3/La0.67Sr0.33MnO3 heterostructures

Jean-Philippe Ansermet, Dirk Grundler, Mohammad Hamdi, Peng Gao, Haiming Yu, Yu Zhang, Jilei Chen, Jianyu Zhang

Magnons can transfer information in metals and insulators without Joule heating, and therefore are promising for low-power computation. The on-chip magnonics however suffers from high losses due to limited magnon decay length. In metallic thin films, it is ...

Nature Research2021

Study on the Performances of AlScN based SAW/BAW Hybrid Resonators A Parametric Analysis of Acoustic Wave Resonators with Large Figure of Merit

Luis Guillermo Villanueva Torrijo, Soumya Yandrapalli, Guilain Lionel Germain Lang

In this study, we analyze a 3rd type of FBAR's fundamental mode by finite element method. We show the importance of the substrate's wave velocity and conductivity on the electromechanical coupling efficiency. Then we demonstrate that etching traditional SA ...

IEEE2021

The 2021 Magnonics Roadmap

Dirk Grundler, Thomas Yu, Heena Yang, Joyeeta Sinha

Magnonics is a budding research field in nanomagnetism and nanoscience that addresses the use of spin waves (magnons) to transmit, store, and process information. The rapid advancements of this field during last one decade in terms of upsurge in research p ...

2021

Simulation of High-Frequency Transients in Overhead Lines Including Frequency-Dependent Soil Parameters: an FDTD Aproach

Farhad Rachidi-Haeri, Rafael Silva Alipio

This paper investigates the effect of frequency-dependent soil parameters on the simulation of electromagnetic transients on overhead lines, based on the application of the FDTD method to solve the telegrapher’s equations. The ground return impedance is ca ...

2021

Effect of Fear of Falling on Mobility Measured During Lab and Daily Activity Assessments in Parkinson’s Disease

Kamiar Aminian, Arash Atrsaei

In chronic disorders such as Parkinson’s disease (PD), fear of falling (FOF) is associated with falls and reduced quality of life. With inertial measurement units (IMUs) and dedicated algorithms, different aspects of mobility can be obtained during supervi ...

2021

An Extension of the Guided Wave M‐Component Model Taking Into Account the Presence of a Tall Strike Object

Farhad Rachidi-Haeri, Marcos Rubinstein, Mohammad Azadifar, Qi Li, Mi Zhou

We present in this paper an extension of the guided-wave M-component model of Rakov et al. considering the presence of a vertically elevated strike object. The tall object is represented as a lossless, uniform transmission line. Expressions for the current ...

2021

Feasibility of Detecting Interstellar Panspermia in Astrophysical Environments

Claudio Grimaldi

The proposition that life can spread from one planetary system to another (interstellar panspermia) has a long history, but this hypothesis is difficult to test through observations. We develop a mathematical model that takes parameters such as the microbi ...

IOP PUBLISHING LTD2021