基于800 nm飞秒激光脉冲对标准单模光纤采用非载氢技术刻写长周期光纤光栅的机理进行了研究.搭建了水平、垂直双CCD视频监控的飞秒激光脉冲逐点刻蚀长周期光纤光栅系统, 研究了光栅长度、激光脉冲能量和光栅占空比等参数对光栅光谱特性的影响.研究结果表明, 当光栅周期长度不变, 光栅周期数和激光脉冲能量的变化使光栅谐振峰强度发生变化, 光栅透射谱是单峰的; 光栅占空比的改变导致光栅谐振峰由单峰转变为多峰.在谐振波长1 540 nm处, 得带谐振峰强度达到15 dB、带外损耗不足2 dB, 在3 dB衰减处带宽为15 nm的谐振透射谱.

The fabrication mechanism of Long-Period Fiber Gratings(LPFGs) in standard SMF-28 telecommunication fibers without hydrogen loading were explored by using direct writing method based on femtosecond laser pulses, with pulse duration of 100 fs, 1kHz repetition rate and a central wavelength of 800 nm. The experimental system to write LPFGs is adopted directly the horizontal and vertical double CCD video to realize monitoring and alignment of fiber. The LPFGs with different spectral characteristics were fabricated by adjusting the number of grating period, energy density of laser irradiation and duty ratio. The result shows that resonance peak loss generate single-peak when the period of grating is constant, and the variations of the number of grating periods and pulse energy of laser irradiation will lead to the change of resonance peak loss. The variations of duty ratio will lead to the generation of resonance rejection band of LPFGs from single-peak to multi-peak plus lesser out-of-band loss. And finally, a resonance transmission spectra with 15 dB attenuation, 3 dB bandwidth of 15 nm, and less than 2 dB out-of-band losses at wavelength of 1 540 nm was obtained.