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利用高频CO2激光脉冲写制了倾斜长周期光纤光栅(TLPFG),运用改造的耦合模理论对基于高频CO2激光脉冲写制的TLPFG进行了理论分析,实验研究了倾斜折射率调制对TLPFG光谱特性的影响,分析了倾斜角度对TLPFG模式耦合特性的影响。实验结果表明,利用高频CO2激光脉冲写制的TLPFG具有新颖的耦合特性,低阶次包层模的耦合系数大于高阶次包层模,倾斜折射率调制不仅可以提高纤芯基模与包层模的耦合系数,还可以激励纤芯基模向高阶包层模式耦合,且随着倾斜角的增大可以明显提高光栅的写制效率。
Tilt long period fiber grating (TLPFG) was written by using high frequency CO2 laser pulses. TLPFG based on high frequency CO2 laser pulse writing was theoretically analyzed by the modified coupled mode theory. The effects of tilt index modulation on TLPFG spectra The influence of tilt angle on the coupling characteristics of TLPFG mode is analyzed. The experimental results show that the TLPFG fabricated by high frequency CO2 laser pulse has a novel coupling characteristic. The coupling coefficient of the low-order cladding modes is higher than that of the higher-order cladding modes. Tilt index modulation can not only improve the performance of the core- Coupling coefficients of the modes can also stimulate the mode coupling of the core-based modes to the higher-order cladding modes. With the increase of the tilt angle, the writing efficiency of the grating can be obviously improved.