Femtosecond laser point-by-point (PbP) technology can be used as a direct writing method to inscribe fiber Bragg gratings (FBGs) into the cladding of optical fibers. When the refractive index modulated area of cladding FBGs (CLFBGs) is close to the core–cladding interface, the CLFBGs exhibit characteristics similar to conventional core-based FBGs. When bending was applied, the reflected power of the CLFBGs changed significantly and showed an orientation dependence on the fiber bending direction. The CLFBG inscription method provides a new opportunity to fabricate vector sensing devices, which can be realized by parallelly inscribed multiple CLFBGs. Compact CLFBGS with a low insertion loss (less than 0.05 dB) have application value in the fields of optical fiber sensors, communications, and lasers.

中文翻译：

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飞秒激光逐点刻划多包层光纤布拉格光栅


飞秒激光逐点（PbP）技术可用作直接写入方法，将光纤布拉格光栅（FBG）刻写到光纤的包层中。当包层光纤光栅（CLFBG）的折射率调制区域靠近纤芯-包层界面时，CLFBG 表现出与传统基于纤芯的光纤光栅类似的特性。当施加弯曲时，CLFBG 的反射功率发生显着变化，并且表现出对光纤弯曲方向的取向依赖性。 CLFBG刻写方法为制造矢量传感器件提供了新的机会，可以通过并行刻写多个CLFBG来实现。紧凑型CLFBGS具有低插入损耗（小于0.05 dB），在光纤传感器、通信、激光器等领域具有应用价值。