Control of electromagnetic (EM) flux and energy is a fundamental

scientific issue with great implications in theory and applications.

Based on the principles of refraction and reflection, lenses and

waveguides composed of dielectrics and metals have become the

most successful devices to guide and control EM waves and

fluxes. Recently, the rapid development in the field of artificial

EM structures such as photonic crystals, plasmonic structures, and

metamaterials has inspired new ways to control EM waves and

fluxes beyond traditional methods, leading to intriguing devices

such as superlens, hyperlens, invisibility cloaks, illusion devices, and

tunneling waveguides. In this chapter, we introduce a mechanism to

control the spatial distribution of either the electric or the magnetic

field instead of both fields. We demonstrate that EM fluxes can

be controlled in an almost arbitrary manner in wavelength and

subwavelength scales. Interestingly, the principle of flux control

in our method does not rely on surface waves as in the field of

plasmonics, but relies on the evanescent waves induced by the

strong anisotropy and designed inhomogeneity of media. Alongwith

the ability of controlling EM flux, such inhomogeneous anisotropic

media exhibit surprisingly robust high transmittance. Combining

with transformation optics, such high transmittance property can

be utilized to build waveguide devices with almost arbitrary shapes

and bending angles. As ourmethod only needs to control the electric

field instead of the magnetic field, it also provides an efficient

approach for flux control with nonmagnetic dielectric media.