Design for High Efficiency Fiber/Waveguide Power Coupler with SU8 Polymer

A method for designing a high efficiency SMF-28 fiber/waveguide power coupler comprised SU8 polymer is proposed and simulated numerically. Theoretically, the significant dissimilarity of the refractive index of a SMF-28 fiber and a SOI waveguide induces the dissimilitude of the mode field profile so that a low coupling efficiency for these two components comes out. In addition, bad alignment of fiber/waveguide interface in azimuthally and horizontal positions also elicits magnificent power coupling loss which is another reason for poor performance of coupler. In this study, we proposed an effective power coupler that consists of SU8 to substitute the silica to lessen the fiber/waveguide coupling loss. The proposed coupler with coupling efficiency of 76% is reachable.