Optical power managed network node for processing dense wavelength division multiplexed optical signals

Abstract

A technique for processing dense wavelength division multiplexed optical signals in a network node is disclosed. In one embodiment, the technique is realized as an optical power managed network node comprising a dense wavelength division multiplexing device for combining a plurality of narrowband optical signals into a multiplexed polychromatic optical signal. The optical power managed network node also comprises a wavelength-selective optical power detector for detecting the power of each of the plurality of narrowband optical signals combined into the multiplexed polychromatic optical signal. The optical power managed network node further comprises a plurality of attenuators for attenuating the power of at least one of the plurality of narrowband optical signals based upon the detected power of each of the plurality of narrowband optical signals.

Description

[0001] This patent application claims priority to U.S. Provisional Patent Application No. 60 / 187,101, filed Mar. 6, 2000, which is hereby incorporated by reference herein in its entirety.[0002] This patent application is related to U.S. patent application Ser. No. 09 / 578,721, filed May 26, 2000, which is hereby incorporated by reference herein in its entirety.[0003] The present invention relates generally to dense wavelength division multiplexing networks and, more particularly, to an optical power managed network node for processing dense wavelength division multiplexed optical signals.[0004] Dense wavelength division multiplexing (DWDM) networks typically comprise a plurality of network nodes for receiving and transmitting dense wavelength division multiplexed optical signals. Each of the plurality of network nodes typically allows an individual optical signal that is contained in a received dense wavelength division multiplexed optical signal to either simply pass through the net...

AI Technical Summary

Benefits of technology

[0012] The primary object of the present invention is to provide an optical power managed network node for processing dense wavelength division multiplexed optical signals in an efficient and cost effective manner.

[0014] According to the present invention, a technique for processing dense wavelength division multiplexed optical signals in a network node is provided. In a first embodiment, the technique is realized as an optical power managed network node comprising a dense wavelength division multiplexing device for combining a plurality of narrowband optical signals into a multiplexed polychromatic optical signal. The optical power managed network node also comprises a wavelength-selective optical power detector for detecting the power of each of the plurality of narrowband optical signals combined into the multiplexed polychromatic optical signal. The optical power managed network node further comprises a plurality of attenuators for attenuating the power of at least one of the plurality of narrowband optical signals based upon the detected power of each of the plurality of narrowband optical signals. The plurality of narrowband optical signals are beneficially attenuated, prior to being combined into the multiplexed polychromatic optical signal, so as to equalize the power in each of the plurality of narrowband optical signals.

[0019] In accordance with still further aspects of the present invention, the multiplexed polychromatic optical signal is preferably a first multiplexed polychromatic optical signal, and the optical power managed network node further beneficially comprises a demultiplexing device for separating a second multiplexed polychromatic optical signal into the second plurality of narrowband optical signals. The wavelength-selective optical power detector may beneficially detect the power of each of the second plurality of narrowband optical signals contained within the second multiplexed polychromatic optical signal. Alternatively, the optical power managed network node may further beneficially comprise a second wavelength-selective optical power detector for detecting the power of each of the second plurality of narrowband optical signals contained within the second multiplexed polychromatic optical signal.

[0020] In an alternative embodiment, the technique is realized as a method for processing dense wavelength division multiplexed signals in an optical power managed network node. The method comprises combining a plurality of narrowband optical signals into a multiplexed polychromatic optical signal, and then detecting the power of each of the plurality of narrowband optical signals combined into the multiplexed polychromatic optical signal. The method also comprises attenuating the power of at least one of the plurality of narrowband optical signals based upon the detected power of each of the plurality of narrowband optical signals. As in the first embodiment of the optical power managed network node described above, the plurality of narrowband optical signals are beneficially attenuated, prior to being combined into the multiplexed polychromatic optical signal, so as to equalize the power in each of the plurality of narrowband optical signals.

[0021] In accordance with other aspects of the present invention, the power of the multiplexed polychromatic optical signal is beneficially adjustably amplified based upon the detected power of each of the plurality of narrowband optical signals.

Problems solved by technology

Also, most existing optical add / drop network nodes typically inflict some degree of loss upon the power of the optical signals that are received at each network node.

All of the above-described demultiplexing, switching, and multiplexing functions typically inflict some degree of loss upon the power of the optical signals that are received at the optical add / drop network node.

Thus, optical signals that are "added" to the network at the optical add / drop network node are also typically subject to multiplexing function losses.

Additionally, differences in power between "added" optical signals and optical signals that are otherwise received at most existing optical add / drop network nodes can cause problems such as, for example, channel crosstalk, in the resulting dense wavelength division multiplexed optical signal that is transmitted further along the network from the optical add / drop network node.

That is, when "added" optical signals are combined (i.e., multiplexed) with optical signals that are otherwise received at the optical add / drop network node, the higher power optical signals often interfere with the lower power optical signals.

Obviously, the above-described manual network initialization procedure can be costly in terms of both time spent by a network operator and the cost of optical power measurement and adjustment equipment.

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