  The polarization controlled optical signal routing has many important
applications in photonics such as polarization beam splitter. By using
two-dimensional transmission lines with lumped elements, we experimentally
demonstrate the selective excitation of guided modes in waveguides composed of
two kinds of single-negative metamaterials. A localized, circularly polarized
emitter placed near the interface of the two kinds of single-negative
metamaterials only couples with one guided mode with a specific propagating
direction determined by the polarization handedness of the source. Moreover,
this optical spin-orbit locking phenomenon, also called the photonic spin Hall
effect, is robust against interface fluctuations, which may be very useful in
the manipulation of electromagnetic signals.
