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用两个周期为600μm,齿宽为200μm的周期性刻槽板彼此错开从上下两面对单模光纤施压,在光纤中形成了微弯式长周期光纤光栅。由于齿宽小于二分之一周期,可产生更深的光纤微弯调制,获得更大的交流交叉耦合系数。通过测量两个光栅长度分别为6 cm和12 cm的微弯式长周期光纤光栅在不同压力下的透射谱,研究了峰值损耗、附加损耗、损耗谱半峰全宽与压力和光栅长度的关系。对于长12 cm的微弯式长周期光纤光栅,在第一饱和压力点峰值损耗达到19.2 dB,损耗谱半峰全宽(FWHM)为20 nm,附加损耗只有0.26 dB;经过三次过耦合得到34 dB的峰值损耗。然后用理论结合实验数据分析发现当光纤所受压力小于饱和压力时,光纤光栅交流交叉耦合系数与压力成正比。
Two periodic groove plates with a period of 600 μm and a tooth width of 200 μm are offset from each other to apply pressure to the single-mode optical fiber from both upper and lower surfaces to form a micro-bent long-period fiber grating in the optical fiber. Since the tooth width is less than one-half the cycle, a deeper optical microbend modulation can be generated resulting in a larger AC cross-coupling coefficient. The relationship between the peak loss, the additional loss, the full width at half maximum of the loss spectrum and the pressure and the grating length was studied by measuring the transmission spectra of the micro-bent long-period fiber gratings with two gratings of 6 cm and 12 cm respectively. . For the long-period fiber grating with a length of 12 cm, the peak loss at the first saturation pressure point reaches 19.2 dB, the full width at half maximum (FWHM) of the loss spectrum is only 20 nm and the additional loss is only 0.26 dB. After three over couplings, dB peak loss. Then with the theory combined with experimental data analysis found that when the optical fiber pressure is less than the saturation pressure, the optical fiber grating AC cross-coupling coefficient is proportional to the pressure.