Low-crosstalk 4-channel coarse WDM filter using silica-based planar-lightwave-circuit

We have demonstrated a 20 nm-spacing 4-channel CWDM waveguide filter, which we fabricated by employing the half-band filter design theory and silica-based PLC fabrication technology. The filter has advantages of compactness, low-loss, low-crosstalk, and a wide passband. This filter comprises a total of 16 MZI stages, which is the largest-scale lattice-form filter yet reported. This filter can be redesigned for 8-channel use or for different wavelength channels. This means that our filter can be employed as a group wavelength channel multi/demultiplexing filter for the DWDM systems. We believe that this wide passband filter will be a key device in optical metro/access networks.