Through Over-Clad Inscription of FBG in CYTOP Optical Fiber Using Phase Mask Technique and 400 nm Femtosecond Pulsed Laser

In this work, we report the inscription of fiber Bragg grating through the over-clad in cyclic transparent fluoropolymer (CYTOP) optical fiber using a phase mask technique and a 400 nm femtosecond pulsed laser. 8 mm-long grating were obtained in less than 20 s with 500 mu Waverage beam power. To investigate the FBG properties and discriminate between the protective over-clad influence and the core-cladding effect, we inscribe FBGs in the fiber with and without the over-clad. We also show that the temperature sensitivity of CYTOP-FBGs with the over-clad depends on the relative humidity, whereas CYTOP-FBGs without the over-clad achieve almost zero sensitivity to humidity and sensitivity to temperature of 26.7 pm/degrees C.

Automated summary

In this study, fiber Bragg gratings were inscribed in the over-clad of CYTOP optical fiber using a phase mask technique and a 400 nm femtosecond pulsed laser. The results showed that the temperature sensitivity of CYTOP-FBGs with the over-clad depended on the relative humidity, while CYTOP-FBGs without the over-clad had a temperature sensitivity of 26.7 pm/°C.