Electromagnetic Characterization of Complex-Shaped Carbon Nanotubes Using Characteristic Mode Analysis

Abstract

Advances in fabrication techniques have recently allowed the synthesis of Carbon Nanotubes (CNTs) with controlled complex shapes. For example, CNTs with one or more branches sprouting off the main CNT axis, forming unique Y-shaped and K-shaped carbon nanostructures, have recently been fabricated. The angle at each junction and the properties of each branch can be varied by the careful control of the fabrication conditions. In addition to their complex shapes, the conductivity of these nanostructures is not uniform especially at the locations of defects and at junctions where the different CNT branches interface. In this work, we calculate the electromagnetic scattering characteristics of carbon nanotubes with complex shapes. Moreover, we quantify the electromagnetic response of these complex carbon nanostructures using Characteristic Mode Analysis (CMA). CMA decomposes the current of a scatterer in terms of a set of fundamental modes, and it evaluates the relative significance of each mode at a certain frequency. By studying the differences in mode behavior, we will use CMA to explain how the electromagnetic response of complex carbon nanostructures, such a Y-shaped and K-shaped nanostructures, differ from that of pristine straight CNTs. These results will pave the way for using these complex CNT nanostructures in novel sensor, nanoelectronics, and smart composites applications.