Abstract: An optical pass-band filtering device comprises a duplicator able to provide duplicates of an optical signal to at least a first and a second output port; a first optical filtering unit connected to the first output port of the duplicator, said unit having a transfer function that decreases between a first pass wavelength and a first cut-off wavelength; a second optical filtering unit, connected to the second output port of the duplicator, said unit having a transfer function that increases between a second cut-off pass wavelength, the second cut-off wavelength being higher than the first; and coupler connected to the first and second optical filtering units that combine the optical signals filtered by said optical filtering units to obtain a filtered optical signal in which the optical band located between the first and second cut-off wavelengths is removed. A related device node using is also provided.