OPTICAL FIBER FOR ABSOLUTELY SINGLE POLARIZATION

摘要

PURPOSE:To propagate only waves of one linear polarization mode with a small loss by providing the first intermediate layers on both sides of a core so that they are brought into contact with the core and providing the second intermediate layers in a clad apart from the core and the first intermediate layers orthogonally to the first intermediate layers so that they face each other. CONSTITUTION:The first intemediate layers 2' are brought into contact with a core 1' and exist only on both sides of the core 1', and the second intermediate layers 3' exist in a clad 4 apart from the core 1' and the first intermediate layers 2' orthogonally to the first intermediate layers 2' so that they face each other. The refractive index of the core 1' is higher than that of the clad 4, and the refractive index of the first intermediate layers 2' is higher than that of the clad 4, and the refractive index of the second intermediate layers 3' is equal to or lower than that of the clad 4; and when a specific refractive index difference between the core and the clad is denoted as DELTA1 and that between the clad and the first intermediate layers is denoted as -DELTA2 and sectional areas of the core and the first intermediate layers are denoted as S1 and S2 respectively, an optical fiber is constituted to satisfy condition ¦DELTA1S1¦<¦-DELTA2S2¦.