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US 5,491,576 AGranted
Dual-wavelength data transmitter for reducing fading in an optical transmission system
AssigneeAT&T Corp.
InventorNeal S. Bergano
Life of this patent
Estimating the term…
Abstract
The problems relating to SNR fading over long optical transmission paths are overcome by dynamically controlling an optical signal source having two signal components each with a different wavelength, where the parameters to be controlled include the wavelengths of the two signal components, the relative and absolute SOPs of the two signal components, and the relative delays between the data patterns carried by the two signal components so that the polarization of the two signal components of the optical signal are continuously reoptimized in the presence of PDL, PMD, PDHB, and fiber nonlinearities.
Claims39
An apparatus for reducing signal-to-noise ratio fading in an optical transmission path, comprising:
- a means for generating an optical signal having a first and a second signal component where said first and second signal components have a wavelength difference .DELTA..lambda.;
- a means for modulating said first and second signal components so that each of said first and second signal components carries substantially identical information in response to a data signal from a data source;
- a means for varying said wavelength difference .DELTA..lambda. in response to a signal representing a predetermined characteristic of said optical signal as received at a remote end of said transmission path;
- a means for varying the phase between said modulated first and second components of said optical signal in response to said signal representing said predetermined characteristic;
- a means for varying the state of polarization of each of said first and second components of said optical signal in response to said signal representing said predetermined characteristic;
- a means for combining said first and second components of said optical signal into a combined optical signal;
- and
- a means for varying the state of polarization of said combined optical signal in response to said signal representing said predetermined characteristic.
5 more elements
An apparatus for reducing signal-to-noise ratio fading in an optical transmission path, comprising:
- a transmitter including
- a means for generating an optical signal having a first and a second signal components where said first and second signal components have a wavelength difference .DELTA..lambda.;
- a means for modulating said first and second signal components so that each of said first and second signal components carries substantially identical information in response to a data signal from a data source;
- a means for combining said first and second components of said optical signal into a combined optical signal;
- a means for launching said combined optical signal into said optical transmission path for transmission to a remote location;
- a means for varying said wavelength difference .DELTA..lambda., in response to a signal representing a predetermined characteristic of said combined optical signal as received at a remote end of said transmission path;
- a means for varying the phase between said modulated first and second components of said optical signal in response to said signal representing said predetermined characteristic;
- a means for varying the state of polarization of each of said first and second components of said optical signal in response to said signal representing said predetermined characteristic;
- a means for varying the state of polarization of said combined optical signal in response to said signal representing said predetermined characteristic;
- a means for receiving said transmitted combined optical signal;
- a means for measuring said predetermined characteristic of said received combined optical signal;
- and
- a means for transmitting said signal representing said predetermined characteristic of said combined optical signal received at said remote location to said transmitter.
10 more elements
A method for reducing signal-to-noise ratio fading in an optical transmission path, the method comprising the steps of:
- transmitting including
- generating an optical signal having a first and a second signal components where said first and second signal components have a wavelength difference .DELTA..lambda.;
- modulating said first and second signal components so that each of said first and second signal components carries substantially identical information in response to a data signal from a data source;
- varying said wavelength difference .DELTA..lambda. in response to a signal representing a predetermined characteristic of said optical signal as received at a remote end of said transmission path;
- varying the phase between said modulated first and second components of said optical signal in response to said signal representing said predetermined characteristic;
- varying the state of polarization of each of said first and second components of said optical signal in response to said signal representing said predetermined characteristic;
- combining said first and second components of said optical signal into a combined optical signal;
- varying the state of polarization of said combined optical signal in response to said signal representing said predetermined characteristic;
- launching said combined optical signal into said optical transmission path for transmission to a remote location;
- receiving said transmitted combined optical signal;
- measuring said predetermined characteristic of said received combined optical signal;
- and
- transmitting signal representing said predetermined characteristic of said combined optical signal received at said remote location to a transmitter.
10 more elements
A method for reducing signal-to-noise ratio fading in an optical transmission system, comprising the steps of:
- generating an optical signal having a first and second signal components where said first and second signal components have a wavelength difference .DELTA..lambda.;
- modulating said first and second signal components so that each of said first and second components carries substantially identical information in response to a data signal from a data source;
- varying said wavelength difference .DELTA..lambda. in response to a signal representing a predetermined characteristic of said optical signal as received at a remote end of said transmission path;
- varying the phase between said modulated first and second components of said optical signal in response to said signal representing said predetermined characteristic;
- varying the state of polarization of each of said first and second components of said optical signal in response to said signal representing said predetermined characteristic;
- combining said first and second components of said optical signal in response to said signal representing said predetermined characteristic;
- and
- varying the state of polarization of said combined optical signal in response to said signal representing said predetermined characteristic.
5 more elements
An apparatus for reducing signal-to-noise ratio fading in an optical transmission system, comprising:
- at least one laser for generating an optical signal having a first and a second signal component where said first and second signal components have a wavelength difference .DELTA..lambda.;
- wherein said at least one laser includes
- wavelength tuning means for varying said wavelength difference .DELTA..lambda. in response to a signal representing a predetermined characteristic of said optical signal as received at a remote end of said transmission path;
- at least one optical modulator for modulating said first and second signal components so that each of said first and second signal components carries substantially identical information in response to a data signal from a data source;
- a variable time delay for varying the phase between said modulated first and second components of said optical signal in response to said signal representing said predetermined characteristic;
- at least one polarization controller for varying the state of polarization of each of said first and second components of said optical signal in response to said signal representing said predetermined characteristic;
- an optical coupler for combining said first and second components of said optical signal into a combined optical signal;
- and
- at least one other polarization controller for varying the state of polarization of said combined optical signal in response to said signal representing said predetermined characteristic.
6 more elements
A method for reducing signal-to-noise ratio fading in an optical transmission system, comprising the steps of:
- transmitting an optical signal having a first and second signal components wherein said transmitting is performed according at least one predetermined transmitting parameter;
- modulating said first and second signal components so that each of said first and second components carries substantially identical information in response to a data signal from a data source;
- and
- varying said at least one predetermined transmitting parameter in response to a signal representing a predetermined characteristic of said optical signal as received at a remote end of said transmission path.
1 more element
Dependencies are inferred from the claim text.