Patent ID: 11879803
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 5:
6. The optical fiber testing device according to claim 4, wherein the calculator calculates the ratio of the change amount by Expression C1,, [
     
      Math
      .
         
      C1
     
     ]
    
   
   
    
   
  
  
   
    
     
      
       τ
       m
      
      
       τ
       n
      
     
     =
     
      
       
        dv
        Bm
       
       /
       dk
      
      
       
        dv
        Bn
       
       /
       dk
      
     
    
   
   
    
     (
     C1
     )
    
   
  
 

wherein τm and τn represent group delay times of the modes per unit length in the optical fiber to be measured in the propagation modes of LPm and LPn, respectively;
τm/τn represents the ratio of the change amount; and vBm and vBn represent the Brillouin Frequency Shift amounts generated in the propagation modes of LPm and LPn, respectively.