Ball lenses are an inexpensive, mechanically compact optical method for
collimating the output of an optical fiber or laser diode; they can also be used for fiber-to-fiber, diode-to-fiber and fiber-to-detector coupling. However, despite some inherent advantages and lower cost, widespread employment of ball lenses in telecom and datacom applications has been limited by the difficulty in depositing high performance anti-reflection (AR) coatings on them, and by some common misperceptions about utility and availability of ball lenses versus other alternatives such as gradient refractive index (GRIN) lenses and aspheric lenses.
This application note reviews the basic optics of ball lenses, and outlines the
advances that have been made in deposition of high performance anti-reflection
(AR) coatings to ball lenses. Also included are a comparison of ball lenses and
GRIN lenses, a brief review of two common applications, and general bonding
and assembly methods. This application note draws heavily upon several