Optical exchanger

Abstract

In addition to the configuration of a conventional optical XC node, a former-stage regenerator for converting optical signals to electrical signals and regenerating optical signals again is provided at an output stage of a demultiplexer and at the input stage of an optical switch unit. Since the regenerator has a 3R function, the regenerator compensates for the influence of the noise and crosstalk generated during propagation in the transmission line, and improves the S/N ratio of the optical signals. Since the optical signals with S/N ratios improved in this way are inputted to the optical switch unit, it is sufficient only if a latter-stage regenerator compensates for the S/N ratio degradation generated in the optical switch unit, and thereby the error rate characteristic of the optical signals can be improved.

What is claimed is:  
     
         1 . An optical exchanger for accommodating a plurality of wavelength-multiplexed input/output optical links, routing wavelength-multiplexed optical signals inputted from each input link, and outputting the optical signals to output links, comprising: 
 demultiplexing means for demultiplexing wavelength-multiplexed optical signals inputted from the input link to optical signals of each wavelength;    first regenerating means for regenerating optical signals of each wavelength outputted from the demultiplexing means;    optical switch means for receiving each input optical signal outputted from the first regenerating means, routing the input and outputting the input optical signals;    second regenerating means for regenerating optical signals of each wavelength outputted from the optical switch means and compensating for an S/N ratio degradation; and    multiplexing means for multiplexing optical signals of each wavelength outputted from the second regenerating means, generating wavelength-multiplexed optical signals and transmitting the optical signals to a transmission line.    
     
     
         2 . The optical exchanger according to  claim 1 , wherein 
 said first regenerating means does not convert the wavelengths of inputted optical signals.    
     
     
         3 . The optical exchanger according to  claim 2 , further comprising; 
 noise elimination filter means for eliminating wavelength components different from inputted optical signals, provided at the former-stage of said second regenerating means and on the output side of said optical switch means.    
     
     
         4 . The optical exchanger according to  claim 1 , wherein 
 when outputting inputted optical signals, said first regenerating means converts the wavelength so that all the wavelengths of the optical signals inputted to said optical switch means are different from each other.    
     
     
         5 . The optical exchanger according to  claim 1 , further comprising; 
 noise elimination filter means for enabling changing of the transmission band thereof, provided at the former-stage of said second regenerating means and on the output side of said optical switch means, wherein 
 said first regenerating means converts the wavelength when regenerating and outputting optical signals so that all the wavelengths of the optical signals inputted to said optical switch means are different from each other.  
   
     
     
         6 . The optical exchanger according to  claim 1 , wherein 
 all the output wavelengths of optical signals from said first regenerating means are the same.    
     
     
         7 . The optical exchanger according to  claim 6 , further comprising: 
 noise elimination filter means for eliminating wavelength components different from inputted optical signals, provided at the former-stage of said second regenerating means and on the output side of said optical switch means.    
     
     
         8 . The optical exchanger according to  claim 1 , further comprising: 
 noise elimination filter means for enabling changing of the transmission band thereof, provided at the former-stage of said second regenerating means and on the output side of said optical switch means, wherein 
 said first regenerating means regenerates and outputs inputted optical signals without converting the wavelengths.  
   
     
     
         9 . An optical exchanger for accommodating a plurality of wavelength-multiplexed input/output optical links, routing wavelength-multiplexed optical signals inputted from each input link, and outputting the optical signals to output links, comprising: 
 a demultiplexer demultiplexing wavelength-multiplexed optical signals inputted from the input link to optical signals of each wavelength;    a first regenerator regenerating optical signals of each wavelength outputted from the demultiplexer;    an optical switch receiving each input optical signal outputted from the first regenerator, routing the input and outputting the input optical signals;    a second regenerator regenerating optical signals of each wavelength outputted from the optical switch and compensating for an S/N ratio degradation; and    a multiplexer multiplexing optical signals of each wavelength outputted from the second regenerator, generating wavelength-multiplexed optical signals and transmitting the optical signals to a transmission line.