WDM OPTICAL NETWORK WITH PASSIVE PASS-THROUGH AT EACH NODE

摘要

A communications network has a plurality of nodes interconnected by an optic al transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium . A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows th e network to be protocol independent. Also, the low losses incurred by the passive filter s permit relatively long path lengths without optical amplification.