Fabrication of high-quality long-fiber Bragg grating by monitoring 3.1-eV radiation (400 nm) from GeO defects

3.1-eV (400-nm) luminescence is generated by UV radiation at 244 nm and guided in a germanium-doped silica fiber. In this letter, we propose a new technique for fabricating a fiber Bragg grating by monitoring the power of this visible light. The UV beam is scanned so as to maximize the visible light caused by the UV radiation. This enables us to fabricate successfully a chirp-free and high quality fiber Bragg grating.