中文摘要：

锥形光纤是直径沿轴向逐渐变化的一种光纤。使用broyden迭代结合打靶法求解了基于熔融拉锥光纤布拉格光栅（FBG）的耦合模方程,数值分析了光纤轴向上的锥度对FBG光谱的影响。与未拉锥的均匀FBG相比,锥形光纤的FBG光谱向短波长处漂移,光谱带宽增大。由于纤芯束缚光场能力变弱,光谱的峰值反射率和透射深度均减小。锥度越大,这种现象越明显。实验中使用拉锥方法制作锥形光纤,通过在相同拉锥长度的情况下改变拉锥速度得到不同锥度的光纤,研究了锥形光纤损耗与拉锥速度的关系。使用波长为248 nm的紫外激光和周期为537 nm的均匀掩模板在所制作的锥形光纤写入布拉格光栅,研究了不同锥度光纤对光栅光谱的影响。实验结果与理论分析结果基本吻合。

英文摘要：

Taper fiber is a kind of fiber with variational diameter along the longitudinal direction.The couple mode equations of fiber Bragg grating（FBG） based on fused taper fiber are solved by numerical method of broyden and shooting,and the effect of taper along the longitudinal direction on spectrum of FBG is analysed.The results show that the spectrum of FBG shifts to short wavelength and the bandwidth broadens because of the effect of taper compared with the condition of uniform FBG.The peak reflectivity and the transmission reduce because the ability of restricting optical power of the fiber core becomes weak.The phenomena become more obvious as the taper becomes bigger.Taper fibers are fabricated by fused taper method,and different taper fibers are obtained through changing the motor velocity on the basis of the same fused taper length.The relation between motor velocity and the loss of the taper fiber is analysed.A Bragg grating is written in taper fiber with 248 nm ultraviolet laser and uniform phase mask of 537 nm,then the effect of different tapers on the spectrum is analysed.The experimental results are consistent with the theoretical results.