Fiber alignment shifts in butterfly laser packaging by laser welding technique: measurement and finite-element-method analysis

The post-weld-shift (PWS) induced fiber alignment shifts of fiber ferrule-clip (FFC) joints in butterfly laser packaging by laser welding technique have been studied experimentally and numerically. There are two designs of clip dimension in the FFC joint: the type I of no gap between clip and ferrule and the type II of 10 μm gap. Using a novel 230x high magnification video probe camera with image acquisition system, the results showed that the fiber shifts of FFC joints with the type II exhibited shifts less than that with the type I. This suggests that the 10 μm gap design may be more suitable for FFC joints than the no gap. The experimental measurements of fiber shifts were in reasonable agreement with the numerical calculations of the finite-element method (FEM) analysis. The major fiber shift formation mechanisms of FFC joints in laser welding process may come from the coefficient of thermal expansion mismatch, the solidification shrinkage, and the residual stresses within the FFC joint. This study has shown that the FEM is an effective method for predicting the PWS induced fiber alignment shifts in butterfly laser packaging.