Ball vs. Gradient Index Lenses

Timothy Clark and Keith Wanser

In modern communications systems, micro-optic components couple light between fibers, from laser diodes to fibers and from fibers to detectors. They also collimate light from fibers in thin-film multiplexing. Both ball lenses and gradient index of refraction lenses will work in these roles.

Ball lenses have enjoyed cost and size advantages over gradient index lenses, but perceptions about relative ease of use have often led communications users to choose gradient index lenses. Because of recent improvements in ball lens coating technology, this preference has diminished. In some cases, ball lenses may even yield higher coupling efficiencies in smaller packages. This is causing a reassessment of the relative merits and has led to an increase in the numbers of ball lenses employed...