Flat designs of impedance-matched nonmagnetic phase transformer and wave-shaping polarization splitter via transformation optics

Based on transformation optics, we propose a method to realize an arbitrary wavefront transformation through an impedance-matched nonmagnetic slab. First, we follow the principle of equal optical path length to realize arbitrary phase transformations by a flat configuration, adopt a nonlinear coordinate transformation to ensure impedance match, and preserve the dispersion relation to render the device nonmagnetic. Applying this method, a phase transformer is designed such that both the wave shape and propagation direction can be changed. Second, we choose distinct deflection angles for two orthogonal polarizations and combine the two sets of material parameters into an anisotropic slab, whereby a wavefront-controllable polarization splitter is achieved. The results are further validated by numerical simulations. The method proposed can be used to develop all-dielectric, lossless and broadband devices that can be easily constructed at optical frequencies.