WDM optical network with passive pass-through at each node
First Claim
1. A communications network employing wavelength division multiplexing comprising:
- a plurality of nodes;
an optical transmission medium interconnecting said nodes, said transmission medium being capable of carrying a plurality of optical signals at distinct wavelengths organized into bands; and
an interface at each node for dropping a band associated therewith, adding a band carrying traffic for another node, and passively forwarding other bands;
wherein said interface includes a filter that passively reflects bands other than band(s) to be dropped at the node, whereby communication can be established directly between a pair of nodes in said network sharing a common band without the active intervention of any intervening node.
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Abstract
A communications network has a plurality of nodes interconnected by an optical 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 the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.
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Citations
20 Claims
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1. A communications network employing wavelength division multiplexing comprising:
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a plurality of nodes;
an optical transmission medium interconnecting said nodes, said transmission medium being capable of carrying a plurality of optical signals at distinct wavelengths organized into bands; and
an interface at each node for dropping a band associated therewith, adding a band carrying traffic for another node, and passively forwarding other bands;
wherein said interface includes a filter that passively reflects bands other than band(s) to be dropped at the node, whereby communication can be established directly between a pair of nodes in said network sharing a common band without the active intervention of any intervening node. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A communications network employing wavelength division multiplexing comprising:
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a plurality of nodes;
an optical transmission medium interconnecting said nodes, said transmission medium being capable of carrying a plurality of optical signals at distinct wavelengths organized into bands; and
an interface at each node for dropping a band associated therewith, adding a band carrying traffic for another node, and passively forwarding other bands;
wherein said interface includes a filter that passively reflects bands other than the band(s) to be dropped at the node, and wherein each node further comprises a fine filter acting as a demultiplexer for subdividing wavelengths within a band dropped by said filter, whereby communication can be established directly between a pair of nodes in said network sharing a common band without the active intervention of any intervening node. - View Dependent Claims (13, 14)
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15. A communications network employing wavelength division multiplexing comprising:
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a plurality of nodes;
an optical transmission medium interconnecting said nodes, said transmission medium being capable of carrying a plurality of optical signals at distinct wavelengths organized into bands; and
an interface at each node for dropping a band associated therewith, adding a band carrying traffic for another node, and passively forwarding other bands;
wherein said interface includes a filter that passively reflects bands other than the band(s) to be dropped at the node, and wherein at least some of the nodes further comprise a cross-connect switch for selectively connecting desired wavelengths with a payload signal, whereby communication can be established directly between a pair of nodes in said network sharing a common band without the active intervention of any intervening node. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification