发现高频CO₂激光脉冲写入的长周期光纤光栅谐振波长的横向负载特性具有较强的负载方向相关性,而损耗峰幅值的横向负载特性的方向相关性较弱.不同圆周方向的横向负载对谐振波长偏振相关性的影响差异较大,但对损耗峰幅值偏振相关性的影响差异较小.利用横向负载引起双折射进而导致光栅的光学主轴旋转的相关理论,合理解释了该长周期光纤光栅独特的横向负载特性及其偏振相关性.

It is demonstrated that the transverse-load characteristic of the resonant wavelength for LPFGs induced by high-frequency CO_2 laser pulses depends strongly on the load-direction, whereas the transverse-load characteristics of the loss peak amplitude is independent on the load-direction. The polarization dependence of the resonant wavelength for the LPFGs is deeply affected by the transverse-load, and the affection depends on load direction, whereas, the polarization dependence of the loss peak amplitude is little affected by the transverse-load. The transverse-load resulted in the optical-axis of the LPFG rotating. The unique transverse-load characteristics of the novel LPFG are analyzed using the theories about the optical-axis rotation, resulting from the load-induced birefringence, of the LPFG.