US5894362A
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US
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Optical communication system which determines the spectrum of a wavelength division multiplexed signal and performs various processes in accordance with the determined spectrum
Assignee: Fujitsu Ltd
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Filing: 1996-08-19
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Granted: 1999-04-13
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Expires: 2016-08-19
Abstract
Abstract An optical communication system for transmitting wavelength division multiplexed (WDM) signal light through an optical fiber. The optical communication system includes a decoupling unit and a monitoring unit. The decoupling unit decouples a portion of the WDM signal light from the optical fiber as a monitoring signal. The monitoring unit determines the spectrum of the WDM signal light from the monitoring signal and performs control processing in accordance with the determined spectrum. Control processing includes performing at least one of the following: (1) controlling light sources to maintain a constant wavelength of each light signal in the WDM signal light, (b) determining a noise figure of an optical amplifier which amplifies the WDM signal light, (c) controlling the optical amplifier to achieve a desired noise figure, (d) detecting a signal-to-noise ratio of the WDM signal light, (e) detecting a true signal power of the WDM signal light, (f) maintaining the true signal power to be at a constant level, (g) counting the number of channels in the WDM signal light, (h) equalizing the gain of an optical amplifier to maintain a flat gain, (i) selecting a light source from among redundant light sources for providing a light signal on a respective channel of the WDM signal light, or (j) selecting a respective channel of the WDM signal light for signal enhancement.
Inventors
- 👤 Hiroshi Onaka
- 👤 Kazue Otsuka
- 👤 Hideyuki Miyata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 07:30
CPC Classifications
H; H04; H04J; H04J14/00; H04J14/02; H04J14/0221; H04B; H04B10/00; H04B10/07; H04B10/075; H04B10/077; H04B10/079; H04B10/0795; H04B10/07953; H04B10/07955; H04B10/07957; H04B10/0799; H04B10/50; H04B10/501; H04B10/506; H04B10/564; H04B10/572; H04J14/0287; H04J14/0297; H04J14/0278; H04J14/0284
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
66 words
An optical communication system transmitting wavelength division multiplexed (WDM) signal light through an optical fiber, comprising: a decoupling unit decoupling a portion of the WDM signal light from the optical fiber as a monitoring signal; and a monitoring unit, connected to the decoupling unit, determining the spectrum of the WDM signal light from the monitoring signal and performing control processing in accordance with the determined spectrum.
Claim 2
Dependent Claim
66 words
An optical communication system transmitting wavelength division multiplexed (WDM) signal light through an optical fiber, comprising: a decoupling unit decoupling a portion of the WDM signal light from the optical fiber as a monitoring signal; and a monitoring unit, connected to the decoupling unit, determining the spectrum of the WDM signal light from the monitoring signal and performing control processing in accordance with the determined spectrum.
Claim 3
Dependent Claim
101 words
An optical communication system as in claim 1, the WDM signal light including a plurality of channels and the optical communication system further comprising: a plurality of light sources corresponding, respectively, to the plurality of channels, each light source providing a light signal at a respective wavelength on the corresponding channel, the light signals being combined to form the WDM signal light, wherein the control processing performed by the monitoring unit includes detecting the respective wavelength of each light signal from the determined spectrum, and controlling the light sources to maintain the detected wavelength of each light signal to be constant.
Claim 4
Dependent Claim
31 words
An optical communication system as in claim 2, wherein the light sources are laser diodes, and the monitoring unit controls the light sources by controlling the temperature of the light sources.
Claim 5
Dependent Claim
94 words
An optical communication system as in claim 2, wherein the monitoring signal includes different wavelength components of the WDM signal light, and the monitoring unit comprises: a dispersion unit receiving the monitoring signal from the decoupling unit and simultaneously dispersing different wavelength components of the WDM signal in different directions, and opto-electric conversion elements at fixed positions for receiving the wavelength components dispersed from the dispersion unit without rotating or moving the dispersion unit, the monitoring unit determining the spectrum of the WDM signal light from wavelength components received by the opto-electric conversion elements.
Claim 6
Dependent Claim
107 words
An optical communication system as in claim 1, further comprising: an optical amplifier receiving the WDM signal light and amplifying the received WDM signal light, wherein the decoupling unit comprises a first decoupler decoupling a portion of the WDM signal light before the WDM signal light is received by the optical amplifier, a second decoupler decoupling a portion of the WDM signal light after the WDM signal light is amplified by the optical amplifier, and a switch receiving the portion decoupled by the first decoupler and the portion decoupled by the second decoupler and being controllable to select one of the received portions as the monitoring signal.
Claim 7
Dependent Claim
119 words
An optical communication system as in claim 5, wherein the control processing performed by the monitoring unit includes controlling the switch of the decoupling unit to select the portion decoupled by the first decoupler and then detecting a signal-to-noise ratio of the WDM signal light from the decoupled portion, the detected signal-to-noise ratio defined as a first signal-to-noise ratio, controlling the switch of the decoupling unit to select the portion decoupled by the second decoupler and then detecting a signal-to-noise ratio of the amplified WDM signal light from the decoupled portion, the detected signal-to-noise ratio defined as a second signal-to-noise ratio, and determining a noise figure from the ratio of the first signalto-noise ratio to the second signal-to-noise ratio.
Claim 8
Dependent Claim
35 words
An optical communication system as in claim 6, wherein the control processing performed by the monitoring unit includes controlling the optical amplifier in accordance with the determined noise figure to achieve a desired noise figure.
Claim 9
Dependent Claim
94 words
An optical communication system as in claim 6, wherein the monitoring signal includes different wavelength components of the WDM signal light, and the monitoring unit comprises: a dispersion unit receiving the monitoring signal from the decoupling unit and simultaneously dispersing different wavelength components of the WDM signal in different directions, and opto-electric conversion elements at fixed positions for receiving the wavelength components dispersed from the dispersion unit without rotating or moving the dispersion unit, the monitoring unit determining the spectrum of the WDM signal light from wavelength components received by the opto-electric conversion elements.
Claim 10
Dependent Claim
80 words
An optical communication system as in claim 1, further comprising: an optical amplifier receiving the WDM signal light and amplifying the received WDM signal light, wherein the decoupling unit decouples, as the monitoring signal, a portion of the WDM signal light after the WDM signal light is amplified by the optical amplifier, and the control processing performed by the monitoring unit includes equalizing the gain of the optical amplifier in accordance with the determined spectrum to maintain a flat gain.
Claim 11
Dependent Claim
94 words
An optical communication system as in claim 9, wherein the monitoring signal includes different wavelength components of the WDM signal light, and the monitoring unit comprises: a dispersion unit receiving the monitoring signal from the decoupling unit and simultaneously dispersing different wavelength components of the WDM signal in different directions, and opto-electric conversion elements at fixed positions for receiving the wavelength components dispersed from the dispersion unit without rotating or moving the dispersion unit, the monitoring unit determining the spectrum of the WDM signal light from wavelength components received by the opto-electric conversion elements.
Claim 12
Dependent Claim
115 words
An optical communication system as in claim 1, further comprising: an optical amplifier receiving the WDM signal light and amplifying the received WDM signal light, wherein the decoupling unit decouples, as the monitoring signal, the portion of the WDM signal light from one of the WDM signal light before the WDM signal light is received by the optical amplifier, and the WDM signal light after the WDM signal light is amplified by the optical amplifier, and the control processing performed by the monitoring unit includes detecting a true signal power of the WDM signal light from the monitoring signal, and controlling the optical amplifier to maintain the detected true signal power at a constant level.
Claim 13
Dependent Claim
42 words
An optical communication system as in claim 11, wherein the monitoring unit detects the true signal power by detecting a signal-to-noise ratio of the WDM signal light from the monitoring signal, and detecting the true signal power from the detected signal-to-noise ratio.
Claim 14
Dependent Claim
42 words
An optical communication system as in claim 1, wherein the WDM signal light includes a plurality of channels, and the control processing performed by the monitoring unit includes determining the number of channels of the WDM signal light from the determined spectrum.
Claim 15
Dependent Claim
57 words
An optical communication system as in claim 13, wherein the determined spectrum indicates the power level of the WDM signal light in a plurality of bands, and the monitoring unit determines the number of channels by counting a number of bands in which the power level of the WDM signal light is greater than a threshold level.
Claim 16
Dependent Claim
71 words
An optical communication system as in claim 14, further comprising: an optical amplifier receiving the WDM signal light and amplifying the received WDM signal light, wherein the decoupling unit decouples the portion of the WDM signal light from one of the WDM signal light before the WDM signal light is received by the optical amplifier, and the WDM signal light after the WDM signal light is amplified by the optical amplifier.
Claim 17
Dependent Claim
79 words
An optical communication system as in claim 13, wherein the determined spectrum indicates the power level of the WDM signal light in a plurality of bands, and the monitoring unit determines the number of channels by forming a differential signal of the determined spectrum and corresponding to changes in the power level of the WDM signal light in the plurality of bands, and counting the number of bands in which the differential signal is greater than a threshold level.
Claim 18
Dependent Claim
70 words
An optical communication system as in claim 16, further comprising: an optical amplifier receiving the WDM signal light and amplifying the received WDM signal light, wherein the decoupling unit decouples the portion of the WDM signal light from one of the WDM signal light before the signal light is received by the optical amplifier, and the WDM signal light after the WDM signal light is amplified by the optical amplifier.
Claim 19
Dependent Claim
75 words
An optical communication system as in claim 1, the WDM signal light including a plurality of channels and the optical communication system further comprising: first and second light sources provided for each channel and being individually selectable to provide a light signal on the channel, wherein the control processing performed by the monitoring unit includes selecting one of the first and second light sources to provide a light signal in accordance with the determined spectrum.
Claim 20
Dependent Claim
94 words
An optical communication system as in claim 1, wherein the monitoring signal includes different wavelength components of the WDM signal light, and the monitoring unit comprises: a dispersion unit receiving the monitoring signal from the decoupling unit and simultaneously dispersing different wavelength components of the WDM signal in different directions, and opto-electric conversion elements at fixed positions for receiving the wavelength components dispersed from the dispersion unit without rotating or moving the dispersion unit, the monitoring unit determining the spectrum of the WDM signal light from wavelength components received by the opto-electric conversion elements.
Claim 21
Dependent Claim
46 words
An optical communication system as in claim 1, wherein the WDM signal light includes a plurality of channels and the control processing performed by the monitoring unit includes selecting a respective channel from the plurality of channels for signal enhancement in accordance with the detected spectrum.
Claim 22
Dependent Claim
26 words
An optical communication system as in claim 20, further comprising: a regenerative repeater regenerating the selected channel, to thereby provide signal enhancement of the selected channel.
Claim 23
Dependent Claim
61 words
An optical communication system as in claim 20, further comprising: a branching device branching the selected channel off the WDM signal light; a regenerative repeater receiving the selected channel from the branching device and regenerating the selected channel; and an insertion unit inserting the regenerated, selected signal back into the WDM signal light, thereby providing signal enhancement of the selected channel.
Claim 24
Dependent Claim
88 words
An optical communication system as in claim 20, further comprising: a branching device branching the selected channel off the WDM signal light; a regenerative repeater receiving the selected channel from the branching device and regenerating the selected channel; a wavelength converter receiving the regenerated, selected channel, and reconstructing a wavelength of the regenerated, selected channel; and an insertion unit receiving the wavelength reconstructed, regenerated, selected channel and inserting the wavelength reconstructed, regenerated, selected channel back into the WDM signal light, thereby providing signal enhancement of the selected channel.
Claim 25
Dependent Claim
94 words
An optical communication system as in claim 20, wherein the monitoring signal includes different wavelength components of the WDM signal light, and the monitoring unit comprises: a dispersion unit receiving the monitoring signal from the decoupling unit and simultaneously dispersing different wavelength components of the WDM signal in different directions, and opto-electric conversion elements at fixed positions for receiving the wavelength components dispersed from the dispersion unit without rotating or moving the dispersion unit, the monitoring unit determining the spectrum of the WDM signal light from wavelength components received by the opto-electric conversion elements.
Claim 26
Dependent Claim
117 words
An optical communication system transmitting wavelength division multiplexed (WDM) signal light through an optical fiber, comprising: a decoupling unit decoupling a portion of the WDM signal light from the optical fiber as a monitoring signal; and a monitoring unit, connected to the decoupling unit, and comprising a dispersion unit receiving the monitoring signal and simultaneously dispersing different wavelength components of the WDM signal in different directions, and receivers at fixed positions for receiving the wavelength components dispersed from the dispersion unit without rotating or moving the dispersion unit, wherein the monitoring unit determines the spectrum of the WDM signal light from wavelength components received by the receivers and performs control processing in accordance with the determined spectrum.
Claim 27
Dependent Claim
117 words
An optical communication system transmitting wavelength division multiplexed (WDM) signal light through an optical fiber, comprising: a decoupling unit decoupling a portion of the WDM signal light from the optical fiber as a monitoring signal; and a monitoring unit, connected to the decoupling unit, and comprising a dispersion unit receiving the monitoring signal and simultaneously dispersing different wavelength components of the WDM signal in different directions, and receivers at fixed positions for receiving the wavelength components dispersed from the dispersion unit without rotating or moving the dispersion unit, wherein the monitoring unit determines the spectrum of the WDM signal light from wavelength components received by the receivers and performs control processing in accordance with the determined spectrum.
Claim 28
Independent Claim
57 words
An method of transmitting a wavelength division multiplexed (WDM) signal light through an optical fiber, comprising the steps of: decoupling a portion of the WDM signal light from the optical fiber as a monitoring signal; determining the spectrum of the WDM signal light from the monitoring signal; and performing control processing in accordance with the determined spectrum.
Claim 29
Independent Claim
57 words
An method of transmitting a wavelength division multiplexed (WDM) signal light through an optical fiber, comprising the steps of: decoupling a portion of the WDM signal light from the optical fiber as a monitoring signal; determining the spectrum of the WDM signal light from the monitoring signal; and performing control processing in accordance with the determined spectrum.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2002-04-12 | 2002-10-12 | 2003-04-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-04-12 | 2006-10-12 | 2007-04-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-04-12 | 2010-10-12 | 2011-04-13 | $7700.00 | Window Closed / Lapsed |