Near 100% Efficient Fiber Microlenses

Abstract

Improving the coupling efficiency between a semiconductor light source and optical fiber is generally achieved by the use of a microlens formed on the end of the fiber [1]. The lens serves to match the modes of the laser and the fiber. The most common way to fabricate microlenses is by tapering the fiber down to a point and melting the end [2]. The resulting lenses are hemispherical in shape and typically collect less than 50% (−3 dB) and at best 55% (−2.5 dB) of the available laser radiation [3]. We have designed and fabricated optimal microlenses for laser-to-fiber coupling that have achieved efficiencies of 90% (−0.45 dB). Nearly 100% coupling is theoretically achievable with this design.