Simultaneous optimization of coupling efficiency and bandwidth of waveguide grating couplers

We analyse the coupling of light between optical fibers and silicon waveguides in the Silicon-On-Insulator (SOI) platform. This platform, providing both high-index contrast and low optical absorption, along with CMOS compatibility, is the leading candidate for the realisation of integrated photonic circuits in silicon[1]. However one outstanding issue is how to couple light from a single-mode optical fiber (which is the optimal system for long distance light propagation) into the SOI waveguide, taking into account the large difference in the lateral dimensions of the modes.