A Notch-Saddle-Compensation Technique in Butterfly-Type Laser Module Packages

A quantitative postweld shift (PWS) correction employing a notch-saddle-compensation technique (NSCT) in a laser-welded butterfly-type laser module package is presented. A predetermined notch geometry is proposed to guide the welding compensation in the specific direction and magnitude precisely. The results show that 82% to 99% of the relative coupling efficiency before welding for the laser modules is achieved by using the NSCT. The fiber shifts due to the PWS can be realigned back closer to their original optimum position after applying the NSCT, and hence, the coupling loss due to the PWS can be regained. In comparison to the published studies on PWS compensation by the mechanical adjustment using the qualitative estimation and plastic deformation, the advantages of using this novel NSCT are the quantitative and nondestructive compensations in butterfly-type laser module packages. Therefore, high-yield butterfly-type laser modules used in lightwave transmission systems are developed and fabricated.