Observations from direct UV-written, non-hydrogen-loaded, thermally regenerated Bragg gratings in double-clad photosensitive fiber

Abstract

In this Letter, experimental evidence is provided for an enhanced thermal sensitivity for a double thermal regeneration feature in fiber Bragg gratings fabricated by direct ultraviolet (UV) writing. Here 47 gratings of varying fluence and wavelength were written along a double-clad, germanium-doped core fiber. Subsequently thermal processing without hydrogen loading the fiber was performed and thermal treatment was carried out in a pure oxygen environment. Thermal sensitivity for the double regeneration increased from 13.6±0.3 pm/°C to 21.3±0.2 pm/°C. Furthermore, one of the highest nominal fluence gratings, #45, exhibited a regeneration factor of 1.73.

Classification of Small-Spot Direct UV Written Fiber Bragg Gratings Through Extreme Thermal Treatment

“…This expands on previous work made by the group [2] and potentially permits harsh environment aerospace deployments to be realized.…”

Thermal approach to classifying sequentially written fiber Bragg gratings

“…Hence, the grating reflection increases at around 400°C. This grating can be seen as a transition from a Type I to Type In grating, which was previously believed to be a double regeneration [15]. Such transitions have been reported in the literature [11].…”

Role of UV fluence on the thermal regeneration characteristics of fiber Bragg gratings: experiment and analysis

“…The strength of a regener ated FBG scales up with seed FBG reflectivity and RI modu lation [20]. The thermal regeneration of an FBG inscribed in double clad nonhydrogenated fiber using frequencydoubled argon-ion laser is also studied [23]. It is shown that the regen eration factor increased by a factor of 1.73 as the fluence increased from 19 kJ cm −2 to 44 kJ cm −2 [23].…”

“…The thermal regeneration of an FBG inscribed in double clad nonhydrogenated fiber using frequencydoubled argon-ion laser is also studied [23]. It is shown that the regen eration factor increased by a factor of 1.73 as the fluence increased from 19 kJ cm −2 to 44 kJ cm −2 [23]. However, a comprehensive study on the role of UV fluence on thermal regeneration characteristics of FBGs written in hydrogenated fiber, and corresponding analysis, is lacking.…”