  A non-unitary transformation leading to a Hatano-Nelson problem is performed
on an array of equally-spaced optical waveguides. Such transformation produces
a non-reciprocal system of waveguides, as the corresponding Hamiltonian becomes
non-Hermitian. This may be achieved by judiciously choosing an attenuation
(amplification) of the injected (or exciting) field. The non-Hermitian
transport induced by such transformation is studied for several cases and
closed analytical solutions are obtained. The corresponding non-Hermitian
Hamiltonian may represent an open system that interacts with the environment,
either loosing to or being provided with energy from the exterior.
