Comparison of active and passive fiber alignment techniques for multimode laser pigtailing

When packaging multimode lasers into low-cost modules, passive fiber alignment would be extremely advantageous especially if the fiber alignment structures could be manufactured using the injection-molding technique. Injection molding as large-volume manufacturing technique allows for the reduction of the unit price of molded parts provided that the number of parts molded by using a single molding tool is large. In this paper, we compare active and passive fiber alignment techniques. The construction and packaging procedures of two modules packaged using active and passive alignment techniques are shown. Using a sleeve construction, a multimode laser with a 230 μm×2 μm emitting area was actively pigtailed with a 100/140-μm multimode fiber. In the other example, a multimode laser with a 300 μm×~1 μm emitting area was passively pigtailed with a 200/230-μm multimode fiber by the use of an alignment structure, which was precision-machined using LIGA technique. The study shows the applicability of the passive alignment technique for low-cost fiber pigtailing