Long-period and fiber Bragg gratings fabricated by high-energy femtosecond pulses

The paper presents the results on long-period and fiber Bragg gratings inscription in non-photosensitive optical fibers by femtosecond radiation with the wavelengths of 513 nm and 1026 nm. The slit beam shaping method is proposed for LPG fabrication to increase the resonant peak amplitude and to reduce the out-of band losses due to smoother profile of refractive index change. The Bragg gratings were inscribed by a point-by-point method through plastic coating of various single mode fibers, SMF-28e+, Fibercore SM1500(9/125)P, Fibercore SM1500SC(9/125)P.