Modified passive alignment of optical fibers with low viscosity epoxy flow running in V-grooves

The alignment of optical fibers is very critical in optoelectronic packaging. A slight offset in any direction may severely affect the performance of the photonic device. Recently, passive alignment of optical fibers has attracted substantial attention due to its lower manufacturing cost and faster processing time when compared with active alignment. For conventional passive alignment, the position of each optical fiber is defined by the geometry of a V-groove. The epoxy is dispensed from the top of the V-groove and another cover plate is usually required to press the fiber against the walls of the V-groove. In the present study, a new technique for epoxy dispensing is developed. Instead of being applied from the top of the V-groove, some low viscosity epoxy is dispensed in a "reservoir" and then flows into the V-groove. Subsequently the epoxy flow runs through the gap between the optical fiber and the V-groove walls. The excess epoxy is diverted to a "canal" next to the "reservoir". It is observed that the flow of epoxy can align the optical fiber by the surface tension. Once the optical fiber is aligned and the epoxy is cured, more epoxy is applied in a glob-top manner to mechanical enhancement. In this paper, the configuration of the V-groove and associated features, the epoxy dispensing process, and the results of alignment are presented in details. Experiments show that the optical fiber, which has more than 60 mum initial misalignment, will align with the centre of the v-grooves within 0.5 mum. By using innovative v-grooves design and epoxy dispensing method, a new way of passive alignment is introduced. It does not require any additional cover plate to press the fiber. The self alignment of the optical fiber is done by a small amount of low viscosity epoxy.