Wide rejection band multidemultiplexer at 1.3-1.55 mu m by cascading high-silica three-waveguide couplers on Si

A novel configuration for an optical guided-wave wide rejection band multidemultiplexer at 1.3 and 1.55 mu m is reported. For a stopband rejection loss of 20 dB, a rejection bandwidth of 160 nm is achieved by cascading and appropriately connecting three high-silica three-waveguide directional couplers on Si. The cascading concept behind the rejection bandwidth improvement is simple and straightforward, and lends itself to a systematic approach for the synthesis of spectral responses for wideband filtering operations.