The silicon on insulator (SOI) is an interesting and promising material for high-density photonic integrated circuits due to its high refractive-index contrast as well as its intrinsic compatibility with the complementary metal-oxide semiconductor (CMOS).[1] However,a major difficulty lies in the coupling of light from or into the waveguide via optical fibers,since the dimensions of waveguides are much smaller than fibers and this results in a huge mismatch in both mode size and shape.Thus efficient coupling of light between the two media cannot be accomplished with the traditional method in which the fiber core is located against the cross section of the silicon waveguide.