Alternative derivations for the fields inside a waveguide

Generally, the longitudinal magnetic field of the transverse electric (TE) wave inside a waveguide is obtained by solving the corresponding Helmholtz wave equation, which further leads to the derivation of the remaining fields. In this paper, we provide an alternative way to obtain this longitudinal magnetic field by making use of one of the Maxwell’s equations instead of directly relying on the Helmholtz wave equation. The longitudinal electric field of the transverse magnetic (TM) wave inside a waveguide can also be derived in a similar fashion. These derivations, which are different from those found in the introductory textbooks on microwave engineering, make the study of waveguides more interesting.

Atomistic simulations of ultra-short pulse laser ablation of aluminum: validity of the Lambert-Beer law

Based on hybrid molecular dynamics/two-temperature simulations, we study the validity of the application of Lambert-Beer’s law, which is conveniently used in various modeling approaches of ultra-short pulse laser ablation of metals. The method is compared to a more rigorous treatment, which involves solving the Helmholtz wave equation for different pulse durations ranging from 100 fs to 5 ps and a wavelength of 800 nm. Our simulations show a growing agreement with increasing pulse durations, and we provide appropriate optical parameters for all investigated pulse durations.

Eigenproblems in nanomechanics

The paper is semitutorial in nature to make it accessible to readers from a broad range of disciplines. Our particular focus is on cataloging the known problems in nanomechanics as eigenproblems. Physical insights obtained from both analytical results and numerical simulations of various researchers (including our own) are also discussed. The paper is organized in two broad sections. In the second section the attention is focused on the analysis of quantum dots. The analysis of electronic properties of strained semiconductor structures is reduced here to the solution of a linear boundary value problem (the classical Helmholtz wave equation). In Sec 3, we provide, intermixed with a literature review, details on various methods and issues in calculation free vibrations/loss of stability for carbon nanotubes. The effect of various parameters associated with the material anisotropy are addressed. Typically classical continuum mechanics, which is intrinsically size independent, is employed for calculations.