Focused electromagnetic beams are frequently modeled by either an angular spectrum of plane waves or a partial-wave sum of spherical multipole waves. The connection between these two beam models is explored here. The partial-wave expansion of an angular spectrum containing evanescent components is found to possess only odd partial waves. On the other hand, the partial-wave expansion of an alternate angular spectrum constructed so as to be free of evanescent components contains all partial waves but describes a propagating beam with a small amount of standing-wave component mixed in. A procedure is described for minimizing the standing-wave component so as to more accurately model a purely forward propagating experimental beam. (c) 2006 Optical Society of America.
Partial-Wave Expansions of Angular Spectra of Plane WavesJournal of the Optical Society of America A: Optics Image Science and Vision
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Citation InformationLock, James A. "Partial-Wave Expansions of Angular Spectra of Plane Waves." Journal of the Optical Society of America A: Optics Image Science and Vision 23 (2006): 2803-2809.