Holmberg Patrik, Laurell Fredrik, Fokine Michael
Opt Express. 2015 Oct 19;23(21):27520-35. doi: 10.1364/OE.23.027520.
A detailed study of the dynamics during thermal regeneration of fiber Bragg gratings, written in hydrogen-loaded standard single-mode fibers using a ns pulsed 213 nm UV laser, is reported. Isothermal pre-annealing performed in the range 85 °C to 1100 °C, with subsequent grating regeneration at 1100 °C, resulted in a maximum refractive index modulation, Δn(m) ~1.4⋅10(-4), for gratings pre-annealed near 900 °C while a minimum value of Δn(m) ~2⋅10(-5) was achieved irrespective of pre-annealing temperature. This optimum denote an inflection point between opposing thermally triggered processes, which we ascribe to the reaction-diffusion mechanism of molecular water and hydroxyl species in silica. The results shed new light on the mechanisms underlying thermal grating regeneration in optical fibers.
本文报道了对用纳秒脉冲213纳米紫外激光写入氢载标准单模光纤中的光纤布拉格光栅热再生过程动力学的详细研究。在85℃至1100℃范围内进行等温预退火，随后在1100℃进行光栅再生，结果表明，对于在900℃附近预退火的光栅，最大折射率调制Δn(m)约为1.4×10⁻⁴，而无论预退火温度如何，Δn(m)的最小值约为2×10⁻⁵。这一最佳值表示相反热触发过程之间的一个拐点，我们将其归因于二氧化硅中分子水和羟基物种的反应扩散机制。这些结果为光纤中热光栅再生的潜在机制提供了新的见解。
