Abstract-Integral equation technique for scatterers with mesoscopic insertions: Application to a carbon nanotube

M. V. Shuba, A. V. Melnikov, P. P. Kuzhir, S. A. Maksimenko, G. Y. Slepyan, A. Boag, A. Mosca Conte, O. Pulci, and S. Bellucci

https://journals.aps.org/prb/accepted/6107dO76Q9410a3e03fb802612edf10544872aa61

We present the electromagnetic scattering theory for a finite-length nanowire with embedded mesoscopic object. The theory is based on a synthesis of the integral equation technique of classical electrodynamics and the quantum transport formalism. We formulate Hall\'en type integral equations, where the canonical integral operators from wire antenna theory are combined with special terms responsible for the mesoscopic structure. The theory is applied to calculate the polarizability of a finite-length single-walled carbon nanotube (CNT) with a short low-conductive section (LCS) in the microwave and sub-terahertz ranges. The LCS is modeled as a multichannel two-electrode mesoscopic system. The effective resistive sheet impedance boundary conditions for the scattered field are applied on the CNT surface. It is shown that the imaginary part of the polarizability spectrum has three peaks. Two of them are in the terahertz range, while the third one is in the gigahertz range. The polarizability spectrum of the CNT with many LCSs has only one gigahertz peak which shifts to low frequencies as the number of the LCS increases. The physical nature of these peaks is explained, and potential applications of nanoantennas are proposed

Abstract-Parameter estimation and imaging of rough surface rotating targets in the terahertz band

Qi Yang; Bin Deng; Ye Zhang; Yuliang Qin; Hongqiang Wang;


https://www.spiedigitallibrary.org/journals/Journal-of-Applied-Remote-Sensing/volume-11/issue-4/045001/Parameter-estimation-and-imaging-of-rough-surface-rotating-targets-in/10.1117/1.JRS.11.045001.short?SSO=1

Research on the scattering behavior of terahertz (THz) waves plays a prominent part in the development of remote sensing and imaging systems. Due to the relatively short wavelengths of THz waves, materials that could be considered smooth at microwave band may begin to display rough surface in the THz region. To study the scattering characteristics and implement parameter estimation and imaging of rough surface rotating targets in the THz band, THz radar systems with carrier frequencies of 220 and 440 GHz were built, and experiments based on a series of rough surface cylinders were carried out. From the time–frequency distributions and imaging results, the transition of scattering characteristics from smooth surface to rough surface is clearly visible, which is consistent with the fact that as the roughness increases, there is an overall increase in diffuse scattering. In addition, methods of rotation period estimation and target size estimation were proposed and applied to experimental data of the THz radar systems, and their validities were verified by the high-precision estimation results.

Abstract-Granular Structure Determined by Terahertz Scattering

Philip Born, Nick Rothbart, Matthias Sperl, Heinz-Wilhelm Hübers
 (Submitted on 23 Dec 2013)
http://arxiv-web3.library.cornell.edu/abs/1312.6519

 Light-scattering in the terahertz region is demonstrated for granular matter. A quantum-cascade laser is used in a benchtop setup to determine the angle-dependent scattering of spherical grains as well as coffee powder and sugar grains. For the interpretation of the form factors for the scattering from single particles one has to go beyond the usual Rayleigh-Gans-Debye theory and apply calculations within Mie theory. In addition to single scattering also collective correlations can be identified and extracted as a static structure factor.