Low-crosstalk 10-GHz-spaced 512-channel arrayed-waveguide grating multi/demultiplexer fabricated on a 4-in wafer

We report a 10-GHz-spaced 512-channel arrayed-waveguide grating (AWG) multi/demultiplexer fabricated on a 4-in wafer. We achieved this by folding the 7-cm-long slab waveguides of a conventionally configured AWG, so that the whole configuration was contained in the wafer and then attached reflecting mirrors at the folded parts. Phase compensation of the fabricated AWG was performed by means of ultraviolet irradiation through a metal mask.