Microfabrication of pre-aligned fiber bundle couplers using ultraviolet lithography of SU-8

This paper describes the design, microfabrication and testing of a pre-aligned array of fiber couplers using direct UV-lithography of SU-8. The fiber coupler array includes an out-of-plane refractive microlens array and two fiberport collimator arrays. With the optical axis of the pixels parallel to the substrate, each pixel of the microlens array can be pre-aligned with the corresponding pixels of the fiberport collimator array as defined by the lithography mask design. This out-of-plane polymer 3D microlens array is pre-aligned with the fiber collimator arrays with no additional adjustment and assembly required, therefore, it helps to dramatically reduce the running cost and improve the alignment quality and coupling efficiency. In addition, the experimental results for the fiber couplers are also presented and analyzed.