School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
Sensors (Basel). 2023 Apr 18;23(8):4064. doi: 10.3390/s23084064.
A five fiber Bragg grating (FBG) array is inscribed at the same spot with a single uniform phase-mask (PM). The inscription setup consists of a near-infrared femtosecond laser, a PM, a defocusing spherical lens and a cylindrical focusing lens. The tunability of the center Bragg wavelength is achieved by a defocusing lens, and by translating the PM, which results in a different magnification of the PM. A first FBG is inscribed, followed by four cascading FBGs, which are inscribed exactly at the same spot only after the translation of the PM. The transmission and reflection spectra of this array are measured, showing a second-order Bragg wavelength at ~1.56 µm with a transmission dip of ~-8 dB. The spectral wavelength shift between each consecutive FBG is ~2.9 nm, and the total wavelength shift is ~11.7 nm. The reflection spectrum of the third-order Bragg wavelength is measured at ~1.04 µm, showing a wavelength separation of ~1.97 nm between neighboring FBGs, and the total spectral span between the first FBG and the last one is ~8 nm. Finally, the wavelength sensitivity to strain and temperature is measured.
在同一位置刻写了一个五光纤布拉格光栅（FBG）阵列和一个单一的均匀相位掩模（PM）。刻写装置由近红外飞秒激光器、PM、离焦球面透镜和柱面聚焦透镜组成。通过离焦透镜实现中心布拉格波长的可调谐性，并通过平移 PM 来实现，这会导致 PM 的放大倍数不同。先刻写一个 FBG，然后再刻写四个级联的 FBG，只有在平移 PM 后才能在同一位置精确刻写。测量了该阵列的透射和反射光谱，在约 1.56 µm 处显示出二阶布拉格波长，透射衰减约为-8 dB。每个连续 FBG 之间的光谱波长移动约为 2.9nm，总波长移动约为 11.7nm。测量了三阶布拉格波长的反射光谱，在约 1.04 µm 处显示出相邻 FBG 之间的波长间隔约为 1.97nm，第一个 FBG 和最后一个 FBG 之间的总光谱跨度约为 8nm。最后，测量了波长对应变和温度的灵敏度。
