Long Working Distance Apodized Grating Coupler

We design a focusing grating coupler by a simultaneous apodization of the filling factor and the period. In addition to in plane focusing to the input waveguide providing a total length of less than 70{\mu}m, a further apodization of the curvature allows out of plane focusing into a fiber set 150{\mu}m away from the grating surface. The design is proposed for novel semiconductor on insulator waveguides such as GaInP. The coupling efficiency is calculated from two dimensional simulation which is about 45%.
Comment: 7 pages, 10 figures