Two slightly shifted gratings are inscribed, one over the other, while exploiting fiber strain in a single-mode fiber. The inscription is done with a near-infrared femtosecond laser, a phase mask, and a cylindrical focusing lens. The first fiber Bragg grating (FBG) is inscribed under normal fiber tension, while the second overlapping FBG is inscribed under higher fiber tension. The transmission spectrum of the complex structure is similar to that of a phase-shifted grating, yet the fabrication process is much faster and simpler compared to other standard methods. A high-quality phase-shifted grating with two $-30\mathrm{dB}$ transmission dips, a 25 dB transmission peak, and $<50\mathrm{pm}$ transmission bandwidth is achieved. We observe polarization-dependent transmission in the phase-shifted gratings.

中文翻译：

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应变辅助的飞秒相移光栅题词

在利用单模光纤中的光纤应变的同时，刻有两个略微偏移的光栅，一个在另一个上。题词是用近红外飞秒激光器，相位掩模和柱面聚焦镜完成的。第一个光纤布拉格光栅（FBG）在正常的光纤张力下被内接，而第二个重叠的FBG在较高的光纤张力下被内接。复杂结构的透射光谱类似于相移光栅的透射光谱，但是与其他标准方法相比，其制造过程要快得多且简单得多。高质量的两相移相光栅$-30\mathrm{D\; b}$ 传输骤降，25 dB传输峰值，以及 $<50\mathrm{下午}$达到传输带宽。我们在相移光栅中观察到偏振相关的透射。