  Darboux-deformations of short range one-dimensional potentials are
constructed by means of Gamow-Siegert functions (resonance states). Results
include both Hermitian and non-Hermitian short range potentials which are
exactly solvable. As illustration, the method is applied to square wells and
barriers for which the transmission coefficient is a superposition of
Fock-Breit-Wigner distributions. Resonance levels are calculated in the long
lifetime limit by means of analytical and numerical approaches. The new complex
potentials behave as an optical device which both refracts and absorbs light
waves.
