Method and device for spectral level balancing in wavelength division multiplex multi-channel systems

Abstract

WDB multi-channel systems for large distances having a number of intensifiers cause an increase in intensification, which can lead to considerable differences in intensity, even given modest wavelength dependence This makes spectral levelling necessary. In accordance with the invention, the light from the fiber is first split spectrally into channels, and, thus locally separated, projected onto the surface of an optic limiter based on an OASLM (optical addressed, spatial light modulator), in which the intensive channels are overproportionally attenuated The tension dependence of liquid crystal cells, derived from exposure, is used to level the WDM channels Lastly, the channels are again imaged onto a point and coupled into another fiber. The invention is used in WDM multi-channel systems for large distances with a number of intensifiers

1 . A method for spectral level balancing in WDM multi-channel systems, 
 characterized in that the light from the fiber is first spectrally split into channels and locally projected separately onto the surface of an optical limiter on the basis of an OASLM (optically addressed spatial light modulator), that the intense channels are disproportionately weakened therein by using the nonlinear voltage dependence, derived from the exposure to the light, of liquid-crystal cells to level the WDM channels; and that the channels are finally imaged again onto a point and are coupled into a further fiber    
     
     
         2  A device for spectral level balancing in WDM multi-channel systems, 
 characterized in that the device is made of spectrally splitting elements built into the fiber and of an optical limiter on the basis of an OASLM (optically addressed spatial light modulator) on the projection surface, which is built directly into the fiber between spectrally splitting elements and imaging elements and produces the proportional voltage at the liquid-crystal cell through exposure of a photoconductor  
 
     
     
         3  The device as recited in  claim 1 , characterized in that the spectrally splitting and imaging elements are convex gratings.  
     
     
         4 . The device as recited in  claim 1 , 
 characterized in that the spectrally splitting elements are fiber gratings provided with anamorphotic lenses on the fiber for imaging.