Low-cross-talk polarization-insensitive 10-GHz-spaced 128-channel arrayed-waveguide grating multiplexer–demultiplexer achieved with photosensitive phase adjustment

We successfully fabricated a polarization-insensitive 10-GHz-spaced 128-channel arrayed-waveguide grating whose cross talk ranged from $-39$ to $-36 \mathrm{dB}$. The optical phases of all arrayed waveguides were adjusted simultaneously by means of a photoinduced refractive-index change under ArF excimer laser irradiation through metal masks.