21,460 research outputs found
Analogy electromagnetism-acoustics: Validation and application to local impedance active control for sound absorption
An analogy between electromagnetism and acoustics is presented in 2D. The
propagation of sound in presence of absorbing material is modeled using an open
boundary microwave package. Validation is performed through analytical and
experimental results. Application to local impedance active control for free
field sound absorption is finally described
Maxwell-Drude-Bloch dissipative few-cycle optical solitons
We study the propagation of few-cycle pulses in two-component medium
consisting of nonlinear amplifying and absorbing two-level centers embedded
into a linear and conductive host material. First we present a linear theory of
propagation of short pulses in a purely conductive material, and demonstrate
the diffusive behavior for the evolution of the low-frequency components of the
magnetic field in the case of relatively strong conductivity. Then, numerical
simulations carried out in the frame of the full nonlinear theory involving the
Maxwell-Drude-Bloch model reveal the stable creation and propagation of
few-cycle dissipative solitons under excitation by incident femtosecond optical
pulses of relatively high energies. The broadband losses that are introduced by
the medium conductivity represent the main stabilization mechanism for the
dissipative few-cycle solitons.Comment: 38 pages, 10 figures. submitted to Physical Review
Perfectly Matched Layer in Numerical Wave Propagation: Factors that Affect its Performance
The perfectly matched layer (PML) boundary condition is generally employed to prevent spurious reflections from numerical boundaries in wave propagation methods. However, PML requires additional computational resources. We have examined the performance of the PML by changing the distribution of sampling points and the PML’s absorption profile with a view to optimizing the PML’s efficiency. We used the collocation method in our study. We found that equally spaced field sampling points give better absorption of beams under both optimal and nonoptimal conditions for low PML widths. At high PML widths, unequally spaced basis points may be equally efficient. The efficiency of various PML absorption profiles, including new ones, has been studied, and we conclude that for better numerical efficiency it is important to choose an appropriate profile
A convergent Born series for solving the inhomogeneous Helmholtz equation in arbitrarily large media
We present a fast method for numerically solving the inhomogeneous Helmholtz
equation. Our iterative method is based on the Born series, which we modified
to achieve convergence for scattering media of arbitrary size and scattering
strength. Compared to pseudospectral time-domain simulations, our modified Born
approach is two orders of magnitude faster and nine orders of magnitude more
accurate in benchmark tests in 1-dimensional and 2-dimensional systems
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