Effect of V-groove side wall feature on epoxy flow in passive alignment of optical fiber

The alignment issue with optical fibers is very important in optoelectronics packaging. A slight offset in any direction could severely affect the optical performance of photonic devices. Nowadays passive alignment of optical fiber has become popular due to its low cost and short processing time. The self-alignment property is another advantage of passive alignment. A recent study states that the dispensing volume and the viscosity are the main factors affecting the yield of passive alignment. On the other hand, the surface feature of the V-groove side wall is another significant factor affecting the fiber alignment. In order to get an optimum surface condition for the V-groove, alignment of the mask pattern to the [110] direction is very important. Slight misalignment between the mask and crystal direction will change the surface profile of the wall, as well as the dimension of the V-groove, and hence affect the alignment of the fiber. In this paper, the effect of mask misalignment and the side wall feature on fiber alignment is studied. V-grooves with no rotation, rotated 1 degrees, 2 degrees and 3 degrees are fabricated by anisotropic etching. Surface profiles are characterized by using an optical profiler. It can be shown that angular misalignment between the pattern and the crystal direction will result in a poor surface profile. An epoxy flow study is carried out to measure the effect of the side wall feature. Experimental results show poor surface profile will reduce the yield of optical fiber passive alignment. The result is useful in optimizing the V-groove fabrication process and the epoxy flow in the passive alignment of optical fiber.