This study proposes a novel, to the best of our knowledge, development of fluorotellurite glass fiber Bragg gratings (FBGs). Shell-like morphology was achieved using a single femtosecond laser pulse illuminated through the fiber’s polymer coating. Different FBG fabrication methods and parameters were systematically studied to optimize performance. The fluorotellurite FBG exhibited a high sensitivity to writing laser power and reflectivity saturation effect in repetitive writing. A low-insertion-loss fluorotellurite FBG with a reflectivity of over 99% and bandwidth of less than 1 nm was successfully inscribed. The flexible inscription methods can write an FBG at any wavelength in the fluorotellurite glass transparent window, and are applicable to infrared fiber lasers or sensors.

中文翻译：

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红外荧光碲酸盐光纤布拉格光栅的直接飞秒激光刻字

据我们所知，这项研究提出了一种新颖的氟碲酸盐玻璃纤维布拉格光栅 (FBG) 的开发。使用单个飞秒激光脉冲通过光纤的聚合物涂层照射，实现了壳状形态。系统地研究了不同的 FBG 制造方法和参数以优化性能。氟亚碲石FBG表现出对写入激光功率的高灵敏度和重复写入中的反射率饱和效应。成功刻印了反射率超过 99% 且带宽小于 1 nm 的低插入损耗氟亚碲石 FBG。灵活的刻字方法可以在氟碲酸盐玻璃透明窗口中写入任意波长的FBG，适用于红外光纤激光器或传感器。