Optimization of epoxy flow for passive alignment of optical fiber arrays

Alignment is very critical in optoelectronic packaging and slightly offset in any direction will affect the performance of the whole system. Optical fiber is one of the most commonly used as light transmitting medium. It is usually coupled with different components such as light source, photo-detector and waveguides. As the core diameter of glass optical fiber is usually small, active alignment is used to ensure the alignment. However, the equipment cost of active alignment is very high and the process time is long. This makes the whole alignment process very expensive and ineffective [1-2]. Recently, passive alignment by utilizing precisely etched V-grooves is getting more common due to its low cost and short cycle time [3-4]. During the passive alignment process, the optical fiber may be lifted up by the buoyancy of the epoxy and hence an extra covering plate is normally required to press the fibers against the wall of V-grooves. The extra plate may introduce several problems. In this paper, an innovative method of dispensing the epoxy is presented. This introduces the self-alignment capability to the conventional passive alignment method. Also by using the new method, the extra covering plate is not required. It is found that the amount of epoxy dispensed is critically in the process. Also the viscosity of the epoxy determines the flow and hence affects the results. In this paper, the effect of the volume and viscosity of epoxy is studied. From the experimental results, the modified passive alignment method is capable of aligning multiple fibers on fiber arrays up to 8 channels up to 1 micron.