Patent ID: 11860406
Assignee: FUJIKURA LTD.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An optical fiber comprising:
a glass portion including a core;
a clad surrounding the core;
a primary coating layer covering the clad; and
a secondary coating layer covering the primary coating layer, wherein
a value of microbend loss characteristic factor FμBL_GΔβ ([GPa−1·μm−2.5/rad8]·10−12) is 6.1 ([GPa−1·μm−2.5/rad8]·10−12) or less when represented by FμBL_GΔβ=FμBL_G×FμBL_Δβ,
wherein geometry microbend loss characteristic FμBL_G ([GPa−1·μm−2.5/rad8]·10−12) of the optical fiber is represented by, F
      
        μ
        ⁢
        BL
        ⁢
        _
        ⁢
        G
      
    
    =
    
      
        
          K
          s
        
        2
      
      
        
          
            H
            f
          
          2
        
        ×
        
          
            D
            0
          
          0.375
        
        ×
        
          
            H
            0
          
          0.625
        
      
    
  

  
    
      
        K
        s
      
      =
      
        
          
            E
            p
          
          ⁢
          
            d
            f
          
        
        
          t
          p
        
      
    
    ,
    
      

    
    ⁢
    
      
        H
        f
      
      =
      
        
          π
          4
        
        ⁢
        
          
            
              E
              g
            
            ⁡
            
              (
              
                
                  d
                  f
                
                2
              
              )
            
          
          4
        
      
    
    ,
    
      

    
    ⁢
    
      
        D
        0
      
      =
      
        
          E
          p
        
        +
        
          
            
              (
              
                
                  t
                  s
                
                
                  R
                  s
                
              
              )
            
            3
          
          ⁢
          
            E
            s
          
        
      
    
    ,
    
      

    
    ⁢
    
      
        H
        0
      
      =
      
        
          π
          4
        
        ⁢
        
          
            E
            s
          
          ⁡
          
            (
            
              
                
                  R
                  s
                
                4
              
              -
              
                
                  R
                  p
                
                4
              
            
            )
          
        
      
    
    ,
  

where
κs (MPa) is a spring coefficient of the primary coating layer,
Hf (MPa·μm4) is a bending rigidity of the glass portion,
D0 (MPa) is a deformation resistance of the secondary coating layer,
H0 (MPa·μm4) is a bending rigidity of the secondary coating layer,
Eg (GPa) is a Young's modulus of the glass portion,
Ep (MPa) is a Young's modulus of the primary coating layer,
Es (MPa) is a Young's modulus of the secondary coating layer,
df (μm) is an outside diameter of the glass portion,
Rp (μm) is a radius of an outer peripheral surface of the primary coating layer,
Rs (μm) is a radius of an outer peripheral surface of the secondary coating layer,
tp (μm) is a thickness of the primary coating layer, and
ts (μm) is a thickness of the secondary coating layer, and
wherein optical microbend loss characteristic FμBL_Δβ (1/(rad/μm)8) of the optical fiber is represented by, F
      
        μ
        ⁢
        BL
        ⁢
        _Δβ
      
    
    =
    
      1
      
        
          (
          Δβ
          )
        
        8
      
    
  
  ,

where Δβ (rad/m) is a propagation constant difference between propagation constant of a waveguide mode propagating through the optical fiber and propagation constant of a radiation mode.