Optical band splitter/combiner and apparatus comprising the same

An optical device for splitting/combining a first and a second continuous optical wavelength bands, each wider than 10 nm, has a first, a second, a third, a fourth and a fifth optical splitting devices optically coupled in cascade and a first, a second, a third and a fourth optical differential delay devices optically coupled to, and interleaved between, the optical splitting devices. A suitable choice of the coupling angles of the splitting devices and of the differential delays of the optical differential delay devices gives to the structure flattened passbands and stopbands and makes the optical device tolerant to fluctuations of the structural parameters. An apparatus includes the optical device for use in fiber-to-the-premises networks.