A lensed-fiber coupling scheme utilizing a graded-index fiber and a hemispherically ended coreless fiber tip

A new configuration of lensed fibers as the coupling between laser diodes and single-mode fibers is proposed. The lensed fiber consists of a hemispherically ended coreless-fiber and a quarter-pitch length of a graded-index fiber. Fabrication is quite simple and rapid. Basic characteristics of the new configuration, including long working distances and wide tolerances, are experimentally verified. The new configuration is suitable for integration-oriented coupling between arrayed laser diodes and an array of single-mode fibers.