Optical power control monitor for multiple wavelength fiber-optic networks
AssigneeInternational Business Machines Corporation
InventorsCasimer M. DeCusatis, Lawrence Jacobowitz
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Abstract
An optical control monitor and a method for adjusting for changes in optical signals transmitted through an optical network. The method comprises the steps of transmitting a set of optical signals through a network, each of the optical signals having a respective wavelength; and tracking changes to said set of signals by passing each of the signals through a filter having a bandpass function, and dithering the filter bandpass about the wavelengths of each of said set of signals to generate filter output signals. The filter output signals are used to adjust the network or the set of optical signals to compensate for said changes.
Claims20
A method of tracking and compensating for changes in a multi-channel, dense wavelength division multiplexing (DWDM) network, comprising
- employing a dither feedback mechanism which uses optical filters that are already part of the network for add/drop functions;
- dithering the center wavelength of each channel in use in the network about the center of a respective optical filter bandpass, and then passing each channel through its optical filter bandpass to obtain a measurement of the optical transfer function (OTF) in the network at any instant in real-time;
- generating feedback signals from said measurements;
- and
- using said feedback signals to adjust the network or the optical channels in the network to compensate for the changes in the optical channels;
- wherein, when the network configuration is changed by adding or dropping wavelengths, the resulting change in the OTF is tracked and said feedback signals are used to compensate for the change by adjusting the wavelengths of the optical channels in the network to maintain a defined optical transfer function in the network.
A method of adjusting for changes in optical signals transmitted through a multi-channel optical network, comprising:
- transmitting a set of optical signals through a network, each of the optical signals having a respective wavelength;
- tracking changes to said set of signals by dithering the center wavelengths of each of said set of signals about the center of a respective optical filter bandpass, and then passing each of the signals through its optical filter bandpass to generate filter output signals;
- and
- using the filter output signals to adjust the network or the set of optical signals to compensate for said changes by adjusting the wavelengths of some of the optical signals in the network to maintain a defined optical transfer function in the network.
A multi-channel optical control monitor comprising:
- a receiver for receiving a set of optical signals, each of the optical signals having a respective wavelength;
- and
- a tracking circuit to track changes to said set of signals, including
- i) a filter having a plurality bandpass functions,
- ii) means for dithering the wavelength of each optical signal about the center of a respective optical filter bandpass, and then to pass each optical signal through its optical filter bandpass to generate filter output signals representing said changes, and
- iii) a control for using the filter output signals to make a defined adjustment to compensate for said changes by adjusting the wavelengths of the optical signals in the network to maintain a defined optical transfer function in the network.
A combination add unit and drop unit for a multi-channel optical network, the combination comprising:
- an add unit comprising means for transmitting a set of optical signals, each of the optical signals having a respective wavelength;
- and a first dither source for dithering at least one of the optical signals;
- and
- a drop unit comprising a receiver for receiving the set of optical signals;
- and
- a tracking circuit to track changes to said set of signals, the tracking circuit including
- a filter having a plurality bandpass functions,
- means for dithering the wavelength of each optical signal about the center of a respective optical filter bandpass, and then to pass each optical signal through its optical filter bandpass to generate filter output signals representing said changes, and
- a control for using the filter output signals to make a defined adjustment to compensate for said changes by adjusting the wavelengths of the optical signals in the network to maintain a defined optical transfer function in the network.
Dependencies are inferred from the claim text.