  We study a quasi-one-dimensional non-reciprocal Hermitian hourglass photonic
lattice that can accomplish multiple functions. Under the effect of
non-reciprocal coupling, this lattice can produce an energy isolation effect,
two kinds of flat bands, and energy band inversion. The excitation and
propagation of a single energy band and multiple energy bands can be realized;
in the flat band condition, the system has compact localized states, and the
flat bands can be excited by a straightforward method. In addition, we
investigate the edge states under the open boundary condition; a double edge
state appears by using a defect in the system. Our findings advance the theory
of energy band regulation in artificial photonic lattices.
