Grating-assisted coupling of optical fibers and photonic crystal waveguides

We propose and analyze a highly efficient method of coupling light from optical fibers to two-dimensional photonic crystal waveguides. Efficient coupling is achieved by positioning of a tapered fiber parallel to the linear defect, where the photonic crystal's cladding functions as a grating coupler and provides field confinement as well. Numerical simulations indicate that better than 90% transmission is possible with a full width at half-magnitude bandwidth of 12nm. It is shown that one can increase the bandwidth by increasing the field overlap between the two waveguides.