Solder-assembled high coupling efficiency single-mode laser modules using micro-heaters and precompensation technique

In this paper, we are proposing a hybrid integration platform, on which a single-mode lensed fiber can be actively aligned to a semiconductor laser, and then solder-attached to the platform with the help of on-board thin-film heaters. We have demonstrated 50% coupling efficiency with conically lensed single-mode fibers, bonded with gold-tin (AuSn) eutectic solder. The loss of alignment due to solder solidification has been carefully measured and compensated during the subsequent correctional alignment step taking advantage of the reworkability feature of the solder-joint. Two types of fiber sub-assemblies have been tested: uncoated bare fiber housed within a metallized ceramic ferrule, and nickel/gold coated bare fiber directly solder-bonded to the platform. Statistical data confirms that in both the cases, 95% of the loss of original coupling was restored by the precompensation technique.