Patent ID: 11927802
Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 6:
7. The optical module according to claim 1, wherein a transmission distance of an MCF that is a seven-core optical fiber is z, coupling of a core mode of a center core of the MCF (coupling from a center core to a center core) is P00(z), coupling of a core mode of an outer core of the MCF (coupling of an outer core i to an outer core i) is Pii(z), and a coupling coefficient is k, and then P00(z) and Pii(z) are expressed by Expression (1) and Expression (2) below, respectively,, P
            00
          
          ⁡
          
            (
            z
            )
          
        
        =
        
          
            4
            7
          
          +
          
            
              3
              7
            
            ·
            
              cos
              ⁡
              
                (
                
                  
                    2
                    ⁢
                    
                      
                        7
                      
                      ·
                      k
                    
                  
                  ⁣
                  
                    ·
                    z
                  
                
                )
              
            
          
        
      
    
    
      
        (
        1
        )
      
    
  
  
    
      
        
          
            
              P
              
                i
                ⁢
                i
              
            
            ⁡
            
              (
              z
              )
            
          
          =
          
            
              
                
                  c
                  4
                
                +
                
                  s
                  4
                
              
              
                3
                ⁢
                6
              
            
            +
            
              1
              4
            
            +
            
              
                
                  
                    c
                    2
                  
                  ⁢
                  
                    s
                    2
                  
                
                
                  1
                  ⁢
                  8
                
              
              ·
              
                cos
                ⁡
                
                  (
                  
                    2
                    ⁢
                    
                      
                        7
                      
                      ·
                      k
                      ·
                      z
                    
                  
                  )
                
              
            
            +
            
              
                
                  
                    s
                    2
                  
                  
                    1
                    ⁢
                    8
                  
                
                ·
                cos
              
              ⁢
              
                {
                
                  
                    (
                    
                      3
                      -
                      
                        7
                      
                    
                    )
                  
                  ·
                  k
                  ·
                  z
                
                }
              
            
            +
            
              
                
                  
                    s
                    2
                  
                  9
                
                ·
                cos
              
              ⁢
              
                {
                
                  
                    (
                    
                      2
                      -
                      
                        7
                      
                    
                    )
                  
                  ·
                  k
                  ·
                  z
                
                }
              
            
            +
            
              
                
                  s
                  2
                
                9
              
              ·
              
                cos
                ⁡
                
                  (
                  
                    
                      7
                    
                    ·
                    k
                    ·
                    z
                  
                  )
                
              
            
            +
            
              
                
                  
                    c
                    2
                  
                  
                    1
                    ⁢
                    8
                  
                
                ·
                cos
              
              ⁢
              
                {
                
                  
                    (
                    
                      3
                      +
                      
                        7
                      
                    
                    )
                  
                  ·
                  k
                  ·
                  z
                
                }
              
            
            +
            
              
                
                  
                    c
                    2
                  
                  9
                
                ·
                cos
              
              ⁢
              
                {
                
                  
                    
                      (
                      
                        2
                        +
                        
                          7
                        
                      
                      )
                    
                    ·
                    k
                  
                  ⁣
                  
                    ·
                    z
                  
                
                }
              
            
            +
            
              
                
                  c
                  2
                
                9
              
              ·
              
                cos
                ⁡
                
                  (
                  
                    
                      7
                    
                    ·
                    k
                    ·
                    z
                  
                  )
                
              
            
            +
            
              
                1
                9
              
              ·
              
                cos
                ⁡
                
                  (
                  
                    3
                    ·
                    k
                    ·
                    z
                  
                  )
                
              
            
            +
            
              
                2
                9
              
              ·
              
                cos
                ⁡
                
                  (
                  
                    2
                    ·
                    k
                    ·
                    z
                  
                  )
                
              
            
            +
            
              
                1
                9
              
              ·
              
                cos
                ⁡
                
                  (
                  
                    k
                    ·
                    z
                  
                  )
                
              
            
          
        
        ,
        and
      
    
    
      
        (
        2
        )
      
    
  

in Expression (1) and Expression (2), a length L in which the crosstalk is suppressed is a length of the transmission distance z of an MCF in which coupling P00(z) of a core mode of a center core of the MCF and coupling Pii(z) of a core mode of an outer core of the MCF are both 0.8 or more.