  Complex potentials are constructed as Darboux-deformations of short range,
radial nonsingular potentials. They behave as optical devices which both
refracts and absorbs light waves. The deformation preserves the initial
spectrum of energies and it is implemented by means of a Gamow-Siegert function
(resonance state). As straightforward example, the method is applied to the
radial square well. Analytical derivations of the involved resonances show that
they are `quantized' while the corresponding wave-functions are shown to behave
as bounded states under the broken of parity symmetry of the related
one-dimensional problem.
