Cascaded GI-fiber chips with a wedge-shaped end for the coupling between an SMF and a high-power LD with large astigmatism

A novel lensed fiber for high-efficiency coupling between a single-mode fiber (SMF) and a high-power laser diode (LD) with large astigmatism of 176 /spl mu/m is proposed and demonstrated. We experimentally confirmed that the proposed lensed fiber had a minimum coupling loss of 2.5 dB including a reflection loss of 0.3 dB at both ends of the fiber. In addition the new configuration had a long working distance of 67 /spl mu/m. We also investigated the tolerance characteristics for various displacements.