Low-loss arrayed-waveguide grating with high indexregions at slab-to-array interface

Planar lightwave circuits in fiber-optic communications

“…Just as segmentation [40], vertical tapering [41], or selective UV exposure [42] (see Figure 9.33) improve the AWG grating efficiency, these techniques can also improve the coupling efficiency to highly sampled output waveguides. They work by reducing the abruptness of the transition from the waveguide array to the slab region.…”