In the fiber-optic modules packaging, the passive alignment can provide mass production, but it also results in low Electro-Optic performance. After using active alignment in packaging, the laser welding is often applied to assemble the module. However, the welding process cause a post-weld-shift (PWS) of fiber. And the laser welding machine is expensive, this will make the module packaging price hard to cost down. A major cost-reduction soldering fixing technique is developed to replace the laser welding. To determine the fabrication tolerances associated with the coupling of a laser diode and a single-mode fiber(SMF), the sensitivity of the coupling efficiency in both linear and angular offsets was measured. In this research, a fiber holder and a gripper have been developed for assembly. And active alignment is used to align the laser diode and SMF under computer control, whereupon a soldering fixing operation joins the fiber holder on the module. During the soldering process, the condition control was provided to keep the deflection steady. After the displacement compensating before soldering, the final displacement is less than 1 ㎛ which keeps the coupling loss within 3dB.

ABSTRACT A DIP (dual-in-line) laser diode module packaging by soldering technique was investigated. We made high coupling efficiency fiber lens under the best arc fusing conditions. The coupling efficiency of fiber lens was obtained 82%, while offset of fiber lens center was less than 0.5mm and curvature radius was about 9mm. We metallized the high coupling efficiency fiber lens, and packaged it in the DIP housing. The components inside the module were uncoated FP (Fabry-Perot) laser chip, p-i-n detector, substrate, and cooler. We made a package process as follows: 1) We utilized the heating apparatus to fix the FP laser, PIN detector, and thermistor on the substrate. 2) We utilized the heating apparatus to make the cooler fixed on the DIP housing and the substrate fixed on the cooler. 3) We utilized the electrothermal heating machine to melt 1.5mm3 indium wire and adjusted the fiber lens by tweezer to couple light into the fiber inside the DIP housing. We obtained the 2.93mW output power and 58.6% coupling efficiency after packaging. The post-soldering-shift resulted from the indium solidification was the most important factor affecting the coupling efficiency. By improving substrate design properly, we could reduce the indium quantity to minimize the solidification effect. The post-soldering-shift should be controlled below 1mm in the transverse axis and below 10 mm in the longitudinal axis, respectively. Finally, We achieved an external cavity fiber grating laser module with 2mW output power, and got an open eye pattern after measuring the DIP transmitter module.