Scattering, trapped modes and guided waves in waveguides and diffraction   gratings
  We suggest the numerical approach to detect eigenfrequencies of trapped modes in waveguides or guided waves in diffraction gratings. At the same time, the approach works perfectly for computation of systems with finitely many scattering channels. The most attractive example concerns the possibility of control on electron transport in nano-dimensions system consisting of a resonator and finitely many adjoined channels due to external variable electric field. 
Valery E. Grikurov