Numerical aperture of multimode fibers by several methods: resolving differences

An industrywide study among members of the Electronic Industries Association was conducted to document differences among three numerical aperture measurement methods. Results on 12 multimode graded index fibers indicate 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 can be used to relate the various methods. >