A method and apparatus is provided for reformatting or interleaving a WDM signal
that includes a plurality of optical channels having a first bandwidth and a first
channel spacing. The method begins by receiving the WDM signal and dividing it
into first and second subsets of optical channels each having a second channel
spacing. Next, the first subset of optical channels are divided into third and
fourth subsets of optical channels each having a third channel spacing. In addition,
the second subset of optical channels is divided into fifth and sixth subsets of
optical channels each having a fourth channel spacing. The third and fifth subsets
of optical channels are combined to generate a first output WDM signal, while the
fourth and sixth subsets of optical channels are combined to generate a second
output WDM signal.
