FABRICATION STUDY ON LOW LOSS OPTICAL FIBERS FOR LONG WAVELENGTH REGION.

Optical fiber fabrication for the long wavelength region was studied. Loss factors were investigated and it was clarified that dopants like P//2O//5 and B//2O//3 affect the loss characteristics in the long wavelength region. Single mode and graded index optical fibers for 1. 3 mu m were fabricated with GeO//2-P//2O//5-SiO//2 core and P//2O//5-B//2O//3-SiO//2 cladding, with low loss below 0. 5 db/km. Bandwidth of graded index optical fibers was obtained higher than 2 GHz multiplied by (times) km. Single mode optical fibers were fabricated for 1. 6 mu m band, with slightly P//2O//5-doped cladding and ultra low loss of 0. 23 db/km was obtained.