Low-loss rectangular-passband multiplexer consisting of a waveguide grating router synchronized to a three-arm interferometer

We propose and demonstrate a design for a lossless rectangular- passband multiplexer with improved passband characteristics. It consists of a waveguide grating router (WGR) synchronized to a three-arm interferometer. It is similar to our previous design of synchronizing a WGR to a two-arm interferometer, except now the passband has even sharper corners. We also show that three arms is the limit for the input interferometer if one wishes to have a compact layout.