Numerical Aperture of Multimode Fibers by Several Methods: Resolving Differences

An industry-wide study among members of the Electronic Industries Association was conducted to document differences between various numerical aperture measurement methods. Results on twelve multimode graded index fibers indicate that systematic differences exist among commonly used far-field and index profile techniques. Differences can be explained by a wavelength dependent factor and choice of definitions. Conversion factors may be used to relate the various methods.