Dual Band Optical Mux/Demux and apparatus comprising the same

An optical device for splitting/combining a first and a second optical wavelength band has a first, a second and a third optical splitting device optically coupled in cascade and a first and a second differential optical delay device optically coupled to, and interleaved between, the optical splitting devices. This structure together with a suitable choice of the coupling coefficients of the splitting devices and of the differential delays of the differential optical delay devices achieves flattened pass bands and stop-bands and makes the optical device tolerant fluctuations of the structural parameters. An apparatus comprising the optical device is also disclosed for use in fiber-to-the-premises networks.