Negative-index gratings formed by femtosecond laser overexposure and thermal regeneration.
Negative-index gratings formed by femtosecond laser overexposure and thermal regeneration.
复制标题
飞秒激光过曝光和热再生形成的负折射率光栅
DOI：
10.1038/srep23379
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发表时间：
2016-03-16
影响因子：
4.6
通讯作者：
Zhang W
中科院分区：
文献类型：
--
作者：
He J;Wang Y;Liao C;Wang C;Liu S;Yang K;Wang Y;Yuan X;Wang GP;Zhang W
我们提出了一种利用800 nm飞秒激光过曝光和热再生制备负折射率光纤布拉格光栅的方法。首先利用飞秒激光通过相位掩模在无氢单模光纤中刻写了正折射率型I-IR光纤光栅，然后利用飞秒激光的过曝光将I-IR光纤光栅制成了高偏振相关相移光纤光栅（P-PSFBG）。随后，将P-PSFBG在800 °C下热退火12小时。在热退火过程中观察到光栅再生，最终获得了高反射率99.22%，超低插入损耗0.08 dB，布拉格波长蓝移0.83 nm，工作温度高达1000 °C的负折射率光纤光栅。进一步的退火测试表明，负折射率光纤光栅的热稳定性低于II型红外光纤光栅，但远高于I型红外光纤光栅。此外，这种负折射率光栅的形成可以由热再生IIA型光敏性引起。
We demonstrate a method for the preparation of negative-index fibre Bragg gratings (FBGs) using 800 nm femtosecond laser overexposure and thermal regeneration. A positive-index type I-IR FBG was first inscribed in H2-free single-mode fibre using a femtosecond laser directed through a phase mask and then a highly polarization dependant phase-shifted FBG (P-PSFBG) was fabricated from the type I-IR FBG by overexposure to the femtosecond laser. Subsequently, the P-PSFBG was thermally annealed at 800 °C for 12 hours. Grating regeneration was observed during thermal annealing and a negative-index FBG was finally obtained with a high reflectivity of 99.22%, an ultra-low insertion loss of 0.08 dB, a blueshift of 0.83 nm in the Bragg wavelength and an operating temperature of up to 1000 °C for more than 10 hours. Further annealing tests showed that the thermal stability of the negative-index FBG was lower than that of a type II-IR FBG, but much higher than that of a type I-IR FBG. Moreover, the formation of such a negative-index grating may result from thermally regenerated type IIA photosensitivity.