Evanescent- and propagating-field distributions from a strongly-focused-wave beam with subwavelength waist w<sub>a</sub>≪λ as a function of polar angle and distance are investigated. Exact amplitudes and intensities of evanescent E<sub>ev</sub> and propagating E<sub>p</sub> fields, including interference terms, are presented both in near- and far-field regions. It is shown that the amplitude of E<sub>ev</sub> decays as exp(−r/w<sub>a</sub>) in the near-field region and that evanescent waves do not contribute to the far field in the forward direction as they do in the transverse directions θ=π/2, even though the oscillating evanescent field of the same strength but opposite in sign to the propagating field exists in the transverse plane.
© 2003 Optical Society of America
Nikolai I. Petrov, "Evanescent and propagating fields of a strongly focused beam," J. Opt. Soc. Am. A 20, 2385-2389 (2003)