Investigation and Comparison of Postweld-Shift Compensation Technique in TO-Can- and Butterfly-Type Laser-Welded Laser Module Packages

The postweld-shift (PWS) compensation techniques employing a laser displacement meter (LDM) in the transistor outline (TO)-Can-type laser-welded laser module package and a high-magnification camera with image capturing system (HMCICS) in the butterfly-type laser-welded laser module packages are quantitatively investigated and compared. The results show that the fiber alignment shifts due to the PWS can be aligned back closer to their original optimum position after applying the proposed compensation techniques, and hence the coupling powers loss due to the PWS could be regained significantly. Comparing with the measured coupling power and the PWS, the results show that the PWS are in the ranges of 0.2-1.6 mum and 2.1-4.2 mum for the TO-Can- and the butterfly-type laser packages, respectively. The reason for having a larger PWS in the butterfly laser package is that the fiber ferrule is not solidly constrained in the vertical direction. In this paper, a coupled thermal-elasto-plasticity model of a finite-element method (FEM) analysis is employed to evaluate the PWS in the TO-Can- and the butterfly-type laser module packages. The simulated results are in good agreement with the measured results and these show that the PWS in the butterfly-type laser packages are larger than those in the TO-Can packages. A combination of the experimental and numerical results has provided a practical design guideline for fabricating reliable and high-yield laser-welded TO-Can- and butterfly-type laser module packages for use in lightwave communication systems