| 摘要 |
PROBLEM TO BE SOLVED: To provide a fiber grating in which the reflectance of a specified wavelength can be enhanced easily without causing an increase in connection loss nor receiving the limit of forming period of Bragg grating. SOLUTION: As the core of an optical fiber subjected to writing is used a core obtained by co-doping Sn having a prescribed concentration (10000-15000 ppm) in addition to Ge having a general concentration equal to the core of an optical fiber to be connected (specific refractive index ratio corresponds to 0.9%)(E-1). By setting the Ge dope quantity equal to the core of the optical fiber to be connected, the increase in connecting loss resulted from the mismatching of Ge concentration is prevented, and by co-doping Sn, the reflectance is significantly increased more than a one formed by doping only Ge having a general concentration without performing high-pressure hydrogen filling, and a high reflectance substantially equal to a one formed by doping Ge having a high concentration (specific refractive index different corresponds to 2.0%) (H-1) is realized. |
