Online Postweld Shift Measurement of Butterfly-Type Laser Module Employing High-Resolution Capacitance Displacement Measurement System

A quantitative postweld shift (PWS) correction employing a high-resolution capacitance displacement measurement system (CDMS) in laser-welded butterfly-type laser module package is demonstrated. The CDMS has a 25.4-nm resolution and enables precise online measurement of the PWS in both the horizontal and vertical directions. By applying a mechanical adjustment to compensate for the magnitude and direction of the PWS measured online by the CDMS, the results show that the fiber tip can be realigned back closer to the original optimum coupling positions. A relative coupling efficiency of the laser modules can be regained up to an average of 88% by using the CDMS. In comparison with the previous studies on the quantitative PWS compensation in laser-welded butterfly-type laser module packages, the advantages of using this novel CDMS are the high-resolution and the online measurements of the PWS in laser-welded butterfly-type laser module packages. Through an in-depth study on the precise online measurement of the PWS employing high-resolution CDMS, it is now possible to fabricate high-yield butterfly-type laser modules for use in lightwave transmission systems and utilization of many other high-yield and low-cost laser-welded photonics module packages.