Transmission wavelength shift of +36 nm observed with Ta2O5-SiO2 multichannel wavelength filters consisting of three-dimensional photonic crystals

We have developed multichannel wavelength filters consisting of three-dimensional photonic crystals, which have multiple filter regions with different transmission wavelengths according to differences in the in-plane lattice constants of the crystals. In this study, we improved the design of the photonic crystal (PC) filters by making use of the photonic-bandgap edge and fabricated PC filters with a Ta₂O₅-SiO₂ material system. This improvement enabled us to obtain a transmission wavelength shift of +36 nm at 1550 nm, which agrees well with the results of finite-difference time-domain simulations. By connecting the multichannel wavelength filters to a 100-GHz-spaced 40-channel arrayed waveguide grating (AWG), we suppressed the crosstalk in the AWG from -40 dB to less than -60 dB.