3D broadband waveguide cloak and light squeezing in terahertz regime.

In this work, by engineering a dielectric layer with gradient thickness in a circular waveguide, we present a simple method of realizing a 3D broadband waveguide cloak at terahertz regime. It is numerically shown that such a proposed device exhibits nearly perfect cloaking performance with a broadband response for transverse electric polarization, and the working mechanism behind the waveguide cloaking is attributed to dynamic evolution of the guided mode. Distinct from all previous cloaks using transformation optics, our proposed cloak scheme only requires isotropic dielectric material and therefore is much easier to implement, which enables more superiorities in potential applications.