Design and performance of expanded mode fiber using microoptics

In order to relax alignment tolerances on single-mode fiber interconnection, we propose an end face treatment to realize an expanded mode fiber. This new technique consists of splicing fibers with various lengths and characteristics. The spot size and coupling properties are analyzed numerically considering the effects of gap, offset, and tilt. Low loss, wide misalignment tolerances, and low cost are achieved. The fabrication process and experiment results are presented. The performance of a connector with this expanded fiber is reported.