Communications network

Abstract

A communications network wherein first and second optical signals can be launched into an optical fiber in respective first and second regions of a transmission window such that controllable filters can be used to selectively recover the first and second optical signals. This partitioning of the transmission window allows two incompatible optical signals to coexist in the same optical fiber.

The invention claimed is:  
     
       1. An optical communications network comprising:
 a first optical source configured, in use, to generate a first optical signal in a first wavelength region, the first optical signal comprising one or more non-coherent optical signals being transmitted at wavelengths associated with a predetermined wavelength grid; 
 a second optical source configured, in use, to generate a second optical signal in a second wavelength region, the second optical signal comprising one or more coherent optical signals; 
 combining means to launch the first optical signal and the second optical signal into an optical fiber; and 
 a separation means which can be configured, in use, to selectively route optical signals in the first wavelength region to a first output port and optical signals in the second wavelength region to a second output port, wherein, in use, the separation means can be controlled to vary the wavelengths defined by at least one of the first wavelength region or the second wavelength region. 
 
     
     
       2. An optical communications network according to  claim 1 , wherein the separation means comprise one or more tunable optical filters. 
     
     
       3. An optical communications network according to  claim 2 , wherein the one or more tunable optical filters have a cut off wavelength, the filters being configured, in use, to selectively route optical signals in the first wavelength region to a first output port and optical signals in the second wavelength region to a second output port. 
     
     
       4. An optical communications network according to  claim 1 , wherein the separation means comprise one or more wavelength selective switches, the switches being configured, in use, to selectively route optical signals in the first wavelength region to a first output port and optical signals in the second wavelength region to a second output port. 
     
     
       5. A method of operating a communications network, the method comprising:
 generating a first optical signal in a first wavelength region, the first optical signal comprising one or more non-coherent signals being transmitted at wavelengths associated with a predetermined wavelength grid; 
 generating a second optical signal in a second wavelength region, the second optical signal comprising one or more coherent optical signals; 
 launching the first optical signal and the second optical signal into a first end of an optical fiber; and at a second end of the optical fiber; 
 selectively routing optical signals in the first wavelength region to a first output port; 
 selectively routing optical signals in the second wavelength region to a second output port; and 
 varying the wavelengths defined by at least one of the first wavelength region or the second wavelength region.