Optical add/drop multiplexer
First Claim
1. An optical device for use in a wavelength division multiplexed optical communication system comprising:
- an optical bandsplitter having a first, second and third ports, said first port configured to receive said wavelength division multiplexed optical signal having a plurality of optical channels each at a respective wavelength, said bandsplitter configured to separate said plurality of optical channels into a first group of one or more of said channels and a second group of one or more of said channels, said bandsplitter outputting said first group of channels at said second port and said second group of channels at said third port;
a first transmission path optically communicating with said second port of said bandsplitter, said first transmission path carrying said first group of optical channels, said first transmission path having positioned therein one or more filtering elements configured to filter a first set of one or more channels within said first group of channels, said first set of channels corresponding to one or more optical channels to be added to said multiplexed optical signal, said filtering elements configured to transmit through channels corresponding to channels within said first group of channels outside of said first set of optical channels;
a second transmission path optically communicating with said bandsplitter, said second transmission path carrying said optical channels associated with said second group of channels; and
an optical combiner having a first, second and third ports, said first port optically communicating with said first transmission path, said second port optically communicating with said second transmission path, said combiner configured to supply said through channels and said second group of channels to said third port.
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Abstract
In accordance with the present invention, an optical device includes a bandsplitter for separating a wavelength division multiplexed signal into a first and second group of channels. Transmission of one or more channels within the first group of channels is suppressed by one or more filtering elements positioned within a transmission path. The one or more suppressed channels correspond to channels to be added to the wavelength division multiplexed signal. By splitting the multiplexed optical signal into separate wavelength bands, channels previously designated as add/drop channels and their associated components, do not have to be altered with the introduction of additional channels into a WDM or DWDM network. An add/drop module optically communicates with the bandsplitter to add/drop one or more of the channels included in the multiplexed optical signal.
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Citations
31 Claims
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1. An optical device for use in a wavelength division multiplexed optical communication system comprising:
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an optical bandsplitter having a first, second and third ports, said first port configured to receive said wavelength division multiplexed optical signal having a plurality of optical channels each at a respective wavelength, said bandsplitter configured to separate said plurality of optical channels into a first group of one or more of said channels and a second group of one or more of said channels, said bandsplitter outputting said first group of channels at said second port and said second group of channels at said third port;
a first transmission path optically communicating with said second port of said bandsplitter, said first transmission path carrying said first group of optical channels, said first transmission path having positioned therein one or more filtering elements configured to filter a first set of one or more channels within said first group of channels, said first set of channels corresponding to one or more optical channels to be added to said multiplexed optical signal, said filtering elements configured to transmit through channels corresponding to channels within said first group of channels outside of said first set of optical channels;
a second transmission path optically communicating with said bandsplitter, said second transmission path carrying said optical channels associated with said second group of channels; and
an optical combiner having a first, second and third ports, said first port optically communicating with said first transmission path, said second port optically communicating with said second transmission path, said combiner configured to supply said through channels and said second group of channels to said third port. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. An optical device for use in a wavelength division multiplexed optical communication system comprising:
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an optical bandsplitter having a first port configured to receive a wavelength division multiplexed optical signal having a plurality of optical channels each at a respective wavelength, said bandsplitter configured to separate said plurality of optical channels into a first passband and a second passband, said bandsplitter supplying channels associated with said first passband to a second port and channels associated with said second passband to a third port;
an optical add/drop module having a first port optically communicating with said bandsplitter, said add/drop module capable of adding and dropping a first set of one or more channels included within said first passband and transmitting through channels corresponding to channels within said first passband outside of said first set of one or more channels to a second port; and
an optical combiner having a first port optically communicating with said third port of said bandsplitter and a second port optically communicating with said add/drop module, said combiner configured to combine said through channels, said added first set of one or more channels, and said channels within said second passband. - View Dependent Claims (28, 29, 30)
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31. An optical add/drop multiplexer comprising:
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an input port configured to receive a multiplexed optical signal including a plurality of optical channels having a spacing X, each of said optical channels at a respective wavelength, said add/drop multiplexer having a first loss tilt over said plurality of optical channels;
an output port;
a plurality of Bragg gratings optically communicating with said input and said output ports, said Bragg gratings configured to suppress transmission of a first group of one or more channels within said multiplexed optical signal from said input port and transmit through channels within said multiplexed optical signal to said output port, each of said gratings having a transmissivity characteristic as a function of wavelength having;
a gap region defined by a difference Y between a first wavelength and a second wavelength, N of said optical channels lying within said gap region where N≈
Y/X;
a loss region associated with a range of wavelengths shorter than said first wavelength;
a high reflectivity region defined by a difference Z between a third wavelength and a fourth wavelength, Q of said optical channels lying within said high reflectivity region where Q≈
Z/X;
said add/drop multiplexer configured to suppress transmission of K optical channels where K>
M, and M=N+Q;
said through channels having at least one channel falling within the range of wavelengths associated with said loss region; and
said add/drop multiplexer having a second loss tilt over said through channels wherein said second loss tilt is less than said first loss tilt if said through channels pass through said plurality of gratings in sequence.
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Specification