Based on the broken spatial symmetry, we propose a novel scheme for
engineering a unidirectional photonic reflector using a one-dimensional atomic
lattice with defective cells that have been specifically designed to be vacant.
By trapping three-level atoms and driving them into the regime of
electromagnetically induced transparency, and through the skillful design of
the number and position of vacant cells in the lattice, numerical simulations
demonstrate that a broad and high unidirectional reflection region can be
realized within EIT window. This proposed unidirectional reflector scheme
provides a new platform for achieving optical nonreciprocity and has potential
applications for designing optical circuits and devices of nonreciprocity at
extremely low energy levels