Aberrations of GRIN-rod lenses in multimode optical fiber devices

The aberrations of graded-refractive-index-rod lenses (GRIN-rod lenses) are analyzed, with particular emphasis on the characteristics and parameter ranges of interest for various multimode optical fiber devices. Ray-tracing calculations are used to present a visual display of the image quality of particular lenses, and aberration theories are used to interpret and to extrapolate those results. Very simple general expressions are developed for the insertion losses of fiber devices as a function of the relevant lens parameters.