Total reflection of optical beams by weakly oscillating dielectric scatterers

It is well known that in quantum mechanics a weak scatterer can act as a perfect reflector provided it oscillates at a specific frequency, which is close to that of the incident particles. This is a Fano resonance, in which case the propagating wave mode destructively interferes with the bound state. Due to the high frequencies of the optical domain, it is not possible to design an optical device, which is based on this effect. However, if the beam propagates in a narrow waveguide with conducting boundaries, then even a weak dielectric scatterer, which oscillates at the frequency difference between the optical frequency and the threshold frequency of the waveguide, can block the optical beam. This frequency difference can be arbitrarily small. A model for such a system is presented and solved exactly numerically without approximations. For a weak scatterer an approximate analytical expression is suggested for the point of perfect reflection. Finally, a physical realization is suggested. This effect can be used for controlling optical beams by submicron devices.