Structural modification in fused silica by a femtosecond fiber laser at 1558 nm

We report on structural modification in fused silica by a novel commercial femtosecond fiber laser with a fundamental wavelength of 1558 nm. The refractive-index change was induced by laser pulses at a repetition rate of 173 kHz and pulse duration of 870 fs. The refractive index change with a magnitude of 1.2 x 10(-3) was estimated from the diffraction efficiencies of an internal grating.