Patent ID: 6996307

Claim:
A hierarchical optical add-drop multiplexer, OADM, apparatus comprising a power-splitter for receiving a multi-wavelength input optical signal and splitting it into a first signal portion to a waveband OADM and a second signal portion to a variable-bandwidth wavelength OADM; the waveband OADM with a coarse granularity for receiving the first signal portion at a first input port, selectively passing one or more wavebands of the received first signal portion, where each waveband includes a group of wavelengths, outputting the non-passed one or more wavebands of the received first signal portion at a drop port, and receiving a second input optical signal at an add port which is combined with passed wavebands to form a first output signal; the variable-bandwidth wavelength OADM with a fine granularity, connected in parallel with the waveband OADM, for receiving the second signal portion at a second input port; providing variable bandwidth by selectively passing one or more wavelengths of a selected one of the one or more non-passed wavebands of the waveband OADM, outputting the non-passed one or more wavelengths at a drop port, and receiving a third input optical signal at an add port which is combined with passed one or more wavelength channels of the multi-wavelength optical signal to form a second output signal; and a combiner for combining the first and second output signals to form an OADM apparatus output signal.