A new lensed-fiber configuration employing cascaded GI-fiber chips

A new scheme is proposed for lensed fibers having high coupling efficiency between laser diodes and single-mode fibers with a long working distance. The new lensed fiber consists of a pair of GI-fiber tips having different focusing parameters. The measured net coupling loss between a laser diode operating at a wavelength of 1.3 /spl mu/m and a single-mode fiber is as low as 1.5 dB. The working distances are around 50 /spl mu/m, much longer than those of conventional lensed fibers.