A novel AWG demultiplexer composed of slabs with islands

We have proposed a low insertion-loss arrayed waveguide grating (AWG) demultiplexer using phase adjustment elements called islands. The refractive index of the island is the same as that of the cladding. The configuration of the island is designed on the basis of a local phase-velocity principle. The demultiplexer optimized by the BPM shows an insertion loss of 1.3 dB using equally spaced islands. Further investigation shows that the use of chirped islands contributes to a low crosstalk level of less than -50 dB, without increasing the number of arrayed waveguides. We are now measuring the properties of the AWG demultiplexer with islands.