title: Vector theory of diffraction by a single-mode fiber: application to mode-field diameter measurements.
abstract: We derive a far-field diffraction integral by (vector) electromagnetic theory; the result differs from the (scalar) Rayleigh-Sommerfeld or Kirchhoff result in that it depends on polarization. For unpolarized light, we derive a factor (1 + cos(2) theta)((1/2))/ radical2 that replaces the usual obliquity factor. Omitting this factor can cause an error of the same order as the measurement uncertainty in determining the mode-field diameter of a single-mode fiber from far-field data.
authors.forename: M
authors.initials: M
authors.lastname: Young
authors.forename: R C
authors.initials: RC
authors.lastname: Wittmann