  We have theoretically and experimentally achieved large-area one-way
transport by using heterostructures consisting of a domain of an ordinary
photonic crystal (PC) sandwiched between two domains of magnetic PCs. The
non-magnetized domain carries two orthogonal one-way waveguide states which
have amplitude uniformly distributed over a large-area. These two waveguide
states support unidirectional transport even though the medium of propagation
is not magnetized. We show both experimentally and numerically that such
one-way waveguide states can be utilized to abruptly narrow the beam width of
an extended state to concentrate energy. Such extended waveguide modes are
robust to different kinds of defects, such as voids and PEC barriers. They are
also immune to the Anderson type localization when large randomness is
introduced.
