Grating Coupler between Perfectly-Vertical Fiber and Si Wire Waveguide Using Tilted Membrane Structure

A grating coupler on silicon-on-insulator waveguide for perfectly-vertical fiber is proposed based on titled membrane structure. A peak coupling efficiency of 40% and 1dB bandwidth of 40nm are obtained for perfectly-vertical fiber. Back-reflections to the SOI waveguide mode and the fiber mode are 2.7% and 2.2%, respectively.