(12) Min Qiu
Royal Institute of Technology (KTH), Sweden.

Title: Transformation Optics and its Application

Abstract:

Recently the advent of artificial electromagnetic (EM) materials, referred to as metamaterials, has opened up many new ways for us to interact with or control EM waves. With metamaterials, not only that we are able to tailor the permittivity and permeability values at our will, but also we can have precise control over the material anisotropy and how all parameters vary with spatial location. However, how to utilize such metamaterials for achieving a desirable macroscopic optical phenomenon remains a challenge. The recently proposed coordinate transformation method (Transformation Optics) provides the very recipe for solving the such design problem. Transformation optics turns out to be a powerful tool to design novel optical devices, understand peculiar optical phenomena, and open new doors to new applications.

In the present talk, I will discuss on designs of a special type of EM devices, invisibility cloaks, deduced from the coordinate transformation technique. The theory for arbitrarily shaped cloaks will be discussed in details, and their perfectness on invisibility is confirmed by using full-wave analytical analysis. The material parameters of arbitrarily shaped cloaks will also be examined closely. We will also cover cylindrical and spherical cloaks and their simplified versions.Then, cylinder-shaped perfect lens deduced from the coordinate transformation method will also be presented. Connaturality between a cylindrical lens and a slab lens with the same thickness and equivalent material parameters is affirmed by comparing their eigen-field transfer functions.We numerically confirm the sub-wavelength imaging capability of such a cylindrical lens with consideration of material imperfection. The advantages of a cylindrical lens include finite structure size and ability to image with magnification or demagnification.

Besides sub-wavelength imaging, its invisibility property implies that a cylindrical lens may also be valuable for non-invasive electromagnetic probing applications. Finally, I will discuss our recent design on perfect tunneling lens based on the transformation optics. In particular, examples of achieve perfect imaging beyond obstacles will be given.