All-fiber periodic filters for DWDM using a cascade of FIR and IIR lattice filters

Infinite impulse response periodic transmission filters based on superimposed chirped fiber Bragg gratings cascaded with finite impulse response periodic filters, based on all-fiber Mach-Zehnder filters, are designed and experimentally demonstrated to have flat amplitude responses and nearly constant in-band group delays. These filters should be useful in dense wavelength division multiplexing systems, especially as interleavers.