US2017192167A1PendingUtilityA1

High Backscattering Waveguides

Assignee: OFS FITEL LLCPriority: Jun 8, 2015Filed: Mar 24, 2017Published: Jul 6, 2017
Est. expiryJun 8, 2035(~8.9 yrs left)· nominal 20-yr term from priority
G01N 21/47G02B 6/02G02B 6/0208G02B 6/02052G01B 11/18G01B 9/0209
66
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Claims

Abstract

A high backscattering fiber comprising a perturbed segment in which the perturbed segment reflects a relative power that is more than three (3) decibels (dB) above Rayleigh scattering. The high backscattering fiber also exhibits a coupling loss of less than 0.5 dB.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
         1 . A high backscattering fiber, comprising:
 a coupling loss of less than 0.5 decibels (dB) when coupled to a transmission fiber; and   a perturbed segment comprising an index perturbation (Δn(x, y, z)) that causes reflection of relative power (R p→r (λ, z, l)) that is greater than three (3) dB above Rayleigh scattering.   
     
     
         2 . The fiber of  claim 1 , wherein: 
       
         
           
             
               
                 
                   
                     R 
                     
                       p 
                       → 
                       r 
                     
                   
                    
                   
                     ( 
                     
                       λ 
                       , 
                       z 
                       , 
                       l 
                     
                     ) 
                   
                 
                 ≈ 
                 
                   
                     1 
                     l 
                   
                    
                   
                     
                        
                       
                         
                           μ 
                           
                             p 
                             , 
                             r 
                           
                         
                          
                         
                           
                             2 
                              
                             π 
                           
                           λ 
                         
                          
                         
                           
                             ∫ 
                             
                               z 
                               - 
                               
                                 1 
                                 2 
                               
                             
                             
                               z 
                               + 
                               
                                 1 
                                 2 
                               
                             
                           
                            
                           
                             Δ 
                              
                             
                                 
                             
                              
                             
                               
                                 n 
                                 z 
                               
                                
                               
                                 ( 
                                 
                                   z 
                                   ′ 
                                 
                                 ) 
                               
                             
                              
                             
                               e 
                               
                                 i2 
                                  
                                 
                                     
                                 
                                  
                                 π 
                                  
                                 
                                     
                                 
                                  
                                 z′ 
                                  
                                 
                                   
                                     
                                       n 
                                       
                                         eff 
                                         , 
                                         p 
                                       
                                     
                                     + 
                                     
                                       n 
                                       
                                         eff 
                                         , 
                                         r 
                                       
                                     
                                   
                                   λ 
                                 
                               
                             
                              
                             
                               dz 
                               ′ 
                             
                           
                         
                       
                        
                     
                     2 
                   
                 
               
                
               
                   
               
               , 
             
           
         
         l represents an integration length;
 n eff,p  represents an effective index corresponding to p; 
 n eff,r  represents an effective index corresponding to r; 
 μ p,r  represents a modal overlap coefficient such that: 
 
       
       
         
           
             
               
                 
                   
                     μ 
                     
                       p 
                       , 
                       r 
                     
                   
                    
                   
                     : 
                   
                 
                 = 
                 
                   
                     ∫ 
                     
                       
                         ∫ 
                         
                           - 
                           ∞ 
                         
                         ∞ 
                       
                        
                       
                         
                           
                             E 
                             p 
                           
                            
                           
                             ( 
                             
                               x 
                               , 
                               y 
                             
                             ) 
                           
                         
                          
                         Δ 
                          
                         
                             
                         
                          
                         
                           
                             n 
                             
                               x 
                               , 
                               y 
                             
                           
                            
                           
                             ( 
                             
                               x 
                               , 
                               y 
                             
                             ) 
                           
                         
                          
                         
                           
                             E 
                             r 
                             ⋆ 
                           
                            
                           
                             ( 
                             
                               x 
                               , 
                               y 
                             
                             ) 
                           
                         
                          
                         dxdy 
                       
                     
                   
                   
                     
                       
                         ∫ 
                         
                           
                             ∫ 
                             
                               - 
                               ∞ 
                             
                             ∞ 
                           
                            
                           
                             
                               
                                  
                                 
                                   
                                     E 
                                     p 
                                   
                                    
                                   
                                     ( 
                                     
                                       x 
                                       , 
                                       y 
                                     
                                     ) 
                                   
                                 
                                  
                               
                               2 
                             
                              
                             dxdy 
                           
                         
                       
                     
                      
                     
                       
                         ∫ 
                         
                           
                             ∫ 
                             
                               - 
                               ∞ 
                             
                             ∞ 
                           
                            
                           
                             
                               
                                  
                                 
                                   
                                     E 
                                     r 
                                   
                                    
                                   
                                     ( 
                                     
                                       x 
                                       , 
                                       y 
                                     
                                     ) 
                                   
                                 
                                  
                               
                               2 
                             
                              
                             dxdy 
                           
                         
                       
                     
                   
                 
               
               , 
             
           
         
       
       wherein:
 E p (x,y) represents eigenmodes of p; 
 E r (x,y) represents eigenmodes of r; and 
 E r *(x,y) represents the conjugate transpose of E r (x,y). 
 
     
     
         3 . The fiber of  claim 1 , wherein R p→r (λ, z, l) is greater than 10 dB above Rayleigh scattering for wavelengths (λ) of:
   1542.5 nm≦λ≦1557.5 nm
 
 
     
     
         4 . The fiber of  claim 1  further comprising an optical pump, the optical pump having a wavelength outside of the range of wavelengths for which relative power is greater than 3 dB above Rayleigh scattering. 
     
     
         5 . The fiber of  claim 1 , wherein:
     n   (total) ( x,y,z )= n   x,y ( x,y )+Δ n   (total) ( x,y,z ),
   wherein;   n x,y (x,y) represents an unperturbed refractive index;
   Δ n   (total) ( x,y,z )=Δ n   (Rayleigh) ( x,y,z )+Δ n ( x,y,z );
 
   Δn(x, y, z) represents a transverse dependence of the index perturbation; and   Δn z (z) represents a longitudinal dependence of the index perturbation.   
     
     
         6 . The fiber of  claim 5 , wherein:
   Δ n ( x,y,z )≧2·10 −7 ; and
   the sensor has a total sensor length that exceeds 119.5 centimeters (cm).   
     
     
         7 . The fiber of  claim 5 , wherein:
   Δ n ( x,y,z )≧2·10 −7 ; and
   R p→r (λ, z, l)≧−80 dB/mm in a wavelength (λ) range of 1550±7.5 nanometers (nm),   
       wherein:
 l=1 millimeter (mm). 
 
     
     
         8 . The fiber of  claim 5 , wherein:
   Δ n ( x,y,z )≧2·10 −6 ;
   l≈0.3 millimeters (mm)   R p→r (λ, z, l)≧−60 dB·(1/mm) in a wavelength (λ) range of 1550±7.5 nanometers (nm).   
     
     
         9 . The fiber of  claim 5 , wherein:
   Δ n ( x,y,z )≧2·10 −7 .

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