Morphology-Dependent Resonances of an Infinitely Long Circular Cylinder Illuminated by a Diagonally Incident Plane Wave or a Focused Gaussian Beam

The S matrix for scattering a diagonally incident focused Gaussian beam by an infinitely long circular cylinder is calculated, and the diagonal and off-diagonal elements of the matrix are physically interpreted. In addition, the TE and TM morphology-dependent resonances of the cylinder for plane-wave incidence are examined, and it is found that the cylinder size parameter at resonance increases as the angle of incidence of the plane wave increases. The size parameter increase is explained in terms of the heuristic model of morphology-dependent resonances. The presence of both TE and TM resonances in each of the epsilon-polarized and mu-polarized partial-wave scattering amplitudes is discussed. This mixing is interpreted in terms of successive polarization-preserving and cross-polarized total internal reflections of the morphology-dependent-resonance wave inside the cylinder. Finally, some novel properties of morphology-dependent resonances produced by Gaussian-beam incidence are predicted. (C) 1997 Optical Society of America.