Polarization-maintaining (pm) double-clad (dc) optical fiber

Abstract

A double-clad (DC) polarization-maintaining (PM) optical fiber comprises a core, an inner cladding, an outer cladding, and stress rods. The core has a core refractive index (n core ). The inner cladding is located radially exterior to the core and has an inner cladding refractive index (n 1 ), which is less than n core . The stress rods are located in the inner cladding, and each stress rod has a stress rod refractive index (n 2 ), which is substantially matched to n 1 . The outer cladding is located radially exterior to the inner cladding. The outer cladding has an outer cladding refractive index (n out ), which is less than n 1 .

1 . A double-clad (DC) polarization-maintaining (PM) optical fiber, comprising:
 a core having a core refractive index (n core );   an inner cladding located radially exterior to the core, the inner cladding having an inner cladding refractive index (n 1 ), n 1  being less than ncore;   a stress region located in the inner cladding, the stress region having a stress region refractive index (n 2 ), n 2  being substantially matched to n 1 ; and   an outer cladding located radially exterior to the inner cladding, the outer cladding having an outer cladding refractive index (n out ), nout being less than n 1 .   
     
     
         2 . The optical fiber of  claim 1 , the stress region being stress rods that exhibit a bow-tie configuration. 
     
     
         3 . The optical fiber of  claim 1 , the stress region being rods that exhibit a panda configuration. 
     
     
         4 . The optical fiber of  claim 1 , the stress region being an elliptical region located radially exterior to the core. 
     
     
         5 . The optical fiber of  claim 1 , the difference between n 1  and n 2  being slightly greater than approximately 0.003. 
     
     
         6 . The optical fiber of  claim 1 , the difference between n 1  and n 2  being between approximately 0.001 and approximately 0.003. 
     
     
         7 - 12 . (canceled)