We study the problem of coupling an electromagnetic beam of any state of coherence and polarization into a multimode optical fiber. Using the well-known concept of the cross-spectral density matrix, we derive a general expression for the coupling efficiency of a stochastic electromagnetic beam into a multimode fiber in terms of the cross-spectral density matrix of the incident beam and another matrix representing field distributions of fiber modes. We apply this result to a specific case in which the incident beam belongs to a broad class of so-called electromagnetic Gaussian Schell-model beams and obtain a simple analytical expression for the coupling efficiency in the case of single-mode fibers. We use this expression to study how coupling efficiency depends on the coherence and polarization properties of the incident beam.
© 2009 Optical Society of America
Coherence and Statistical Optics
Original Manuscript: August 10, 2009
Manuscript Accepted: September 22, 2009
Published: October 27, 2009
Mohamed Salem and Govind P. Agrawal, "Effects of coherence and polarization on the coupling of stochastic electromagnetic beams into optical fibers," J. Opt. Soc. Am. A 26, 2452-2458 (2009)