A novel fiber alignment shift measurement and correction technique in laser-welded laser module packaging

A novel measurement and correction technique employing an ultra-high-precision laser displacement meter (LDM) with a 20-nm resolution to probe the postweld-shift (PWS)-induced fiber alignment shifts in laser-welded laser module packaging is presented. The results show that the direction and magnitude of the fiber alignment shifts induced by the PWS in laser-welded laser module packaging can be quantitatively determined by four parameters: the lateral position (r), the position angle (α), the swing angle (θ), and the tilt angle (ψ). Further studies show that the deformation of the lateral shift and the position angle are the dominant mechanisms that determine the fiber alignment shifts induced by the PWS. This clearly indicates that the PWS can be quantitatively corrected timely by applying a single weld spot on the negative lateral shift and the position angle to compensate for the fiber alignment shifts. In comparison with previous studies of the PWS correction by a qualitatively estimated technique, this LDM technique has significantly provided an important tool for quantitative measurement and correction to the effect of the PWS on the fiber alignment shifts in laser-welded laser module packaging. Therefore, the reliable laser modules with high yield and high performance used in low-cost lightwave transmission systems may be developed and fabricated.