Negative index and indefinite media waveguide couplers

We study the coupling interaction between dielectric waveguides and coupling elements made from negative-refracting media. The coupling configuration consists of a length of dielectric waveguide, which terminates either directly into or near a planar layer composed of the negative-refracting medium, and is followed by a second waveguide. Radiation output from the first waveguide is refocused at the position of the second waveguide, so that the negative-refracting layer serves as a coupler between the waveguides. Because both isotropic negative-index layers and bilayers of indefinite media can recover the near-field, evanescent components of a source field distribution, the coupling between the input and output waveguides can be highly efficient - in principle providing perfect, lossless coupling. We present simulations and some initial experimental results illustrating the coupling effect, and speculate on the potential for optical fiber couplers and integrated modulators.