Optimal direct coupling from single-mode fibers to Ti:LiNbO3 channel waveguides

We investigate the optimal direct coupling from single-mode fibers To Ti:LiNbO3 channel waveguides using a very general formula and a heuristic optimization technique in this article. The coupling efficiency of the optical power depends on both the fiber positions and the modal sizes of the incident fields. From our numerical simulation, it is found that the optimal positions of the fiber axes are not in alignment with the peak of the waveguiding modal fields and that the coupling efficiency can be improved by microlenses.