Optical transmission systems using optical amplifiers and wavelength division multiplexing
AssigneeNorthern Telecom Limited
InventorsKim Byron Roberts, Maurice Stephen O'Sullivan, Gregory Dean May
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Abstract
The invention provides a method and system for transmitting very high bit rates over an optical link, using unidirectional and bidirectional WDM technology. The 1550 nm window for optical transmission is spatially separated into two bands, "Red" and "Blue", and the channels in each band are selected so that respective wavelengths present a substantially equal gain tilt. A fiber amplifier designed according to spatial separation and wavelength selection of the invention is disclosed, along with multiple span WDM network topologies.
Claims13
A multi-channel telecommunication system comprising:
- (K) first band transmitters at a first site;
- (K) first band receivers at a second site;
- (M) second band receivers at said first site;
- (M) second band transmitters at said second site;
- an optical working fiber (W) connecting said first site and said second site for transporting (K) first band optical signals in a forward direction between said (K) first band transmitters at said first site and said (K) first band receivers at said second site and for transporting (M) second band optical signals in a reverse direction between said (M) second band transmitters at said second site and said (M) second band receivers at said first site;
- a first splitter element at said first site for routing said (K) first band optical signals from said (K) first band transmitters to a first end of said working fiber (W) and for routing said second band optical signals from said first end to a respective one of said (M) second band receivers, according to wavelength;
- a second splitter element for routing said (M) second band optical signals from said (M) second band transmitters to a second end of said optical working fiber (W) and for routing said (K) first band optical signals from said second end to a respective one of said (K) first band receivers, according to wavelength;
- a WDM optical amplifier module series connected on said optical working fiber (W) for amplifying said (K) first band optical signals and said (M) second band optical signals, said WDM optical amplifier module series having
- a first peripheral gain region for amplifying said first band optical signals and said second band optical signals;
- a first three-port WDM splitter connected to said first peripheral gain region for spatially separating said first band optical signals from said second band optical signals, according to wavelength;
- a central gain region for receiving said first band optical signals and said second band optical signals, separately amplifying same;
- a second three-port WDM splitter connected to said central region for spatially separating said first band optical signals from said second band optical signals;
- and
- a second peripheral gain region connected to said second three-port WDM splitter for amplifying said second band optical signals.
A method for transmitting multi-channel optical signals between a first and a second node of a transmission link connected over an optical fiber, comprising the steps of:
- defining a first transmission band associated with a direction of transmission and a second transmission band associated with the opposite direction of transmission;
- selecting (K) forward channels in said transmission band and (M) reverse channels in said transmission band, all said channels having a substantially similar gain tilt/dB;
- transferring, between said first node and a first end of said fiber, a first multi-channel optical signal comprising all said (K) forward channels in said first transmission band, and a second multi-channel optical signal comprising all said reverse channels in said second transmission band;
- providing a WDM optical amplifier module on said fiber;
- at the site of said WDM optical amplifier module, spatially separating said first multi-channel optical signal along a first unidirectional route within said WDM optical amplifier module, and said second multi-channel optical signal along a second unidirectional route within said WDM optical amplifier module, in accordance with the wavelength;
- and
- separately amplifying said first multi-channel optical signal and said second multi-channel optical signal in said WDM optical amplifier module.
Dependencies are inferred from the claim text.