Adiabatically tapered holey fibers are shown to be potentially useful for guided-wave spot-size and numerical-aperture conversion. Conditions for adiabaticity and design guidelines are provided in terms of the effective-index model. We also present finite-difference time-domain calculations of downtapered holey fiber, showing that large spot-size conversion factors are obtainable with minimal loss by use of short, optimally shaped tapers.
© 2001 Optical Society of America
G. E. Town and J. T. Lizier, "Tapered holey fibers for spot-size and numerical-aperture conversion," Opt. Lett. 26, 1042-1044 (2001)