Linearly tapered waveguides on SOI for optical interconnect waveguide-to-fiber coupling

For optical interconnecting waveguides to fiber array coupling, we study a linearly tapered silicon-on-insulator (SOI) waveguide with analyzing the input spot-sizes and the launching positions. In this paper, three cases of the linearly tapered waveguide are compared for indicating optimal light coupling by beam propagation simulations. The best spot size is 4 micrometers with input position (0,4) micrometers for 9 micrometers height Si guiding layer. We also simulate the transverse and longitudinal offset effect for coupling loss analysis between a fiber and the linearly tapered waveguide. The coupling losses can be minimized with properly choosing the longitudinal offset.