PURPOSE: To facilitate work and to prevent unnecessary residual stress from being generated by composing the optical fiber of a core made of a quartz rod having a higher refractive index than a jacket and a refractive index adjusting part surrounded with a stress inducing member.
CONSTITUTION: The optical fiber consists of the jacket 10 with a refractive index n10, core 11 as an optical propagation path which is made of the quartz rod having the higher refractive index n11 than the refractive index n10, stress inducing member 12 with a refractive index n12, and refractive index adjusting part 13 with a refractive index n13 other than the core 11 and stress inducing member 12 in the jacket 10. Consequently, the stress inducing member 12 gives stress anisotropy to the core 11 to obtain birefringence. Further, the stress inducing member 12 with the refractive index n12 is present in the (x) direction of the core 11 with the refractive index n11, and the refractive index adjusting part 13 with the refractive index n13 is present at the part surrounded with the internal surface of the jacket 10, core 11, and stress inducing member 12 in the (y) direction of the core 11. Consequently, the refractive index of the periphery of the core 11 has anisotropy, and consequently birefringence is obtained as well.
MASUNO KUNIO
ABE TAKAHIRO
