Compact optical waveguide coupler using homogeneous uniaxial medium

We introduce the homogeneous transformation optics method into the design of a compact two dimensional (2D) beam coupler. Only homogeneous, nonmagnetic dielectric materials are required, and the fabrication process will thus be simplified. As designed, the coupler can well preserve the beam profile, with the volume significantly smaller than traditional non-transformed ones. It also excels in reducing reflectance and thus significantly increases the transmission efficiency. The coupler, with potential application in micro- and nanoscale photonics, can be applied into the design of an optoelectronic circuit that strongly requires compact volume. It can also be used as a compact squeezer or expander to adjust the radius of an optical beam, to couple with other photonic and/or electronic devices. (C) 2011 Optical Society of America