Patent ID: 6925266

Claim:
An optical wavelength division multiplex transmission unit comprising: (a) several optical transmission elements with respectively one optical transmission spectrum of different center wavelength, the output signal of which is respectively fed to one optical input port of an optical wavelength monitoring and coupling unit that combines the output signals into a wavelength division multiplex signal on one or more optical outputs; (b) wherein the wavelength monitoring and coupling unit is designed such that: an optical path, on which a narrow-band high-pass filtering or low-pass filtering takes place, exists between one, more or all input ports, to which the output signal of a transmission element is fed, and one or more output ports that are not connected to transmission elements; and with respect to the center wavelengths of the filter characteristics, each of the output ports is connected to an optical reception element, wherein every second port of the wavelength division multiplex transmission unit is an output port; (c) wherein the filter characteristic on the path are chosen such that the entire spectral power of the signal filtered with the chosen characteristic changes during a shift in the center wavelength of the transmission spectrum of a transmission element, the signal of which is fed into this path; (d) one or more optical reception elements that are respectively connected to one of the output ports and detect the filtered optical signal appearing at the output ports; and (e) an evaluation and control unit, to which the output signal of the at least one reception element is fed, with said evaluation and control unit evaluating the signal of the reception element in order to determine the position and/or control the position of the transmission spectrum of one or more of the optical transmission elements.