PURPOSE: To provide a forming method of a fiber type diffraction grating for increasing the reflectance of an optical component of a specific wavelength and a fiber for forming diffraction grating.
CONSTITUTION: An optical fiber 10 is mounted in a reaction core tube 20 set to ≥50°C, the gaseous hydrogen (H2) is made to flow in from valve 21 side to a valve 22 and simultaneously the reaction core tube 20 is made to a high temp. high pressure state. The optical fiber 10 is a usual quartz-system optical fiber with a core part containing germanium oxide (GeO2). The concn. of hydrogen to be added into the core part of the optical fiber 10 is preferably ≥500ppm. The large change of refractive index in the irradiation zone of ultraviolet ray is generated by the reducing treatment of an optical waveguide with gaseous hydrogen and the addition of hydrogen to the core part.
INAI MAKI
ENOMOTO TADASHI
INOUE SUSUMU
MOBARA MASAICHI
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