渐变光栅区长度和形状对双锥型FBG光谱特性的影响

Effects of the length and shape of the tapering region on spectral characteristics of the biconical FBGs

提出一种双锥型光纤光栅(FBG),利用传输矩阵方法分析了其渐变光栅区长度和形状对光栅反射谱的影响规律。研究表明:随着渐变光栅区长度的增大,两主峰中间的次级峰幅值按不同比例增大,中间部分比例大,两侧比例小。当渐变光栅区长度增大1个数量级后,中间次峰有明显的交联趋势,随着长度进一步增大,中间次峰完全连接在一起,并与两个主峰等幅变化;渐变光栅区为线性和指数两种形状时,双锥型FBG光谱分布几乎相同,而当渐变光栅区为抛物线形状时,各次级峰右移至右侧主峰两侧,且幅度以主峰为中心逐渐降低。利用实验初步验证了理论分析的正确性。

The effects of the tapering region length and shape on the spectral characteristics of the biconi- cal fiber Bragg grating （FBG） are analyzed using transfer matrix method. The simulation results show that with the increase of the length of the tapering region, the secondary peak amplitudes between the two main peaks increase in different proportions, and there is a larger proportion in the rniddle part. When the tapering region length increases by an order of magnitude, the middle peaks have an obvious series trend. With the length increases, the middle peaks fully connect together, and the two main peaks impolitely change. When the tapering region is a linear and exponential shape, the optical spectrum of the biconical FBG is almost the same, and when the tapering region is a parabolic shape, the secondary peaks shift to the right side of the main peak, and the amplitude of the peak decreases gradually.