Abstract: This paper proposes a direct, pointbypoint inscription of long period fiber gratings (LPFGs) in standard communication coated fibers using an infrared femtosecond laser. The characteristics of axial strain of the coated LPFGs are investigated theoretically and experimentally. The results show that the presence of coating not only strengthens the mechanical robustness but also effectively reduces the shift of the resonant wavelength caused by an applied strain. The coated LPFGs can be modified as bandreject filter and gain equalizer, which show good mechanical reliability and strain stability of resonant wavelength

Key words:  long period fiber grating (LPFG), coating, femtosecond laser, fiber sensing