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针对啁啾Bragg光栅存在的时延线性度差,色散曲线不够平稳等问题,首先从耦合模理论出发,研究折射率调制深度Δn、光栅长度L、啁啾系数C等重要参数对其时延、色散特性的影响,深入探讨参数与特性的关系。提出分段变迹优化方法,探寻了有效的变迹函数和变迹比例。数值分析表明,Δn从10~(-5)到10~(-3),L从5到100mm变化时,时延和色散振荡幅度都逐渐变大,零色散波长都向长波长方向漂移,最大时延差分别为1080、2784ps,时延线性区域逐渐增大,3dB带宽分别从0.75到2.17nm,0.73到1.04nm。C从0.01到0.2nm/cm变化时,时延振荡幅度和线性部分斜率减小,最大时延差明显减小,线性区域增大,带宽从0.18增大到1.52nm。分段变迹优化后时延线性区域增大,色散曲线更平稳,且有效降低了带宽的压缩程度。
Aiming at the problems of chirped Bragg grating, such as poor linearity and unstable chromatic dispersion curve, firstly, from the coupled-mode theory, the effects of important parameters such as depth of modulation of refractive index Δn, grating length L, chirp coefficient C, Dispersion characteristics of the impact of in-depth discussion of the relationship between parameters and characteristics. The method of sectional apodization optimization is proposed, and the effective apodization function and apodization ratio are explored. Numerical analysis shows that when Δn varies from 10 -5 to 10 -3 and L varies from 5 to 100 mm, both the time delay and the dispersion oscillation amplitude gradually increase, and the zero-dispersion wavelength shifts to the long wavelength direction with the maximum The delay differences are 1080 and 2784 ps, respectively, and the time delay linear region gradually increases. The 3dB bandwidth ranges from 0.75 to 2.17 nm and from 0.73 to 1.04 nm respectively. When C is varied from 0.01 to 0.2 nm / cm, the delay oscillation amplitude and the slope of the linear part decrease, the maximum delay difference decreases significantly, the linear region increases and the bandwidth increases from 0.18 to 1.52 nm. After the section apodization is optimized, the time delay linear region increases, the dispersion curve is more stable, and the compression degree of the bandwidth is reduced effectively.