Multiple bound states in sharply bent waveguides

We present experimental and theoretical results on bound states in rectangular bent waveguides. Such bound states can be observed in electromagnetic waveguides and quantum wires. For a class of bent waveguides one can produce confined TE modes; such TE modes are directly related to bound states of scalar fields in the curved two-dimensional space from which the waveguides are constructed. For sufficently sharp bends, one can produce multiple bound TE modes. We calculate the bound-state energies and field configurations for a particular class of sharply bent waveguides. These waveguides are constructed, and both bound-state energies and fields are directly measured and compared with theoretical predictions.