提出了采用遗传算法(GA)结合传输矩阵法从需要的时延特性对光纤光栅进行参数重构的方法。该方法以时延为目标函数,由光纤光栅参数,包括光栅长度、折射率调制、光栅周期和光栅啁啾,组成种群中的待优化的个体,经过若干代遗传得到最优结果。用实值编码遗传算法实现了对均匀光纤光栅、啁啾光纤光栅和切趾啁啾光纤光栅参数的重构。数值仿真结果表明该方法对光纤光栅的时延特性参数重构十分有效。由斜率为100 ps/nm,最大时延为300 ps,中心波长为1555.2 nm的理想线性时延特性重构出切趾啁啾光纤光栅的参数。此方法可以有效地从时延信息中提取光纤光栅参数,能够应用在利用光纤光栅时延特性的光控相控阵天线设计中。

A new method of parameter reconstruction for fiber gratings from desired time-delay characteristics is presented by genetic algorithm (GA) in conjunction with the transfer matrix method in this paper. The objective function in this method is time-delay of fiber gratings, and the individuals of population are the parameters of fiber gratings, including the grating length, refractive index modulation, grating period and grating chirp. The optimal solution is obtained through many generations calculation. The real-coded genetic algorithm is used for parameter reconstruction of uniform, chirped and apodized fiber gratings. Numerical simulating results show that the method is very effective for parameter reconstruction of fiber gratings according to desired time-delay characteristics. An apodized chirped fiber grating is reconstructed from an ideally linear time-delay characteristics whose slope is 100 ps/nm, maximum time-delay is 300 ps and center wavelength is 1555.2 nm. The method proposed can effectively obtain the parameters of fiber gratings from time-delay figures, and can be applied in the design of optically controlled phased-array antennas based on the time-delay characteristics of fiber gratings.