单轴晶体包层啁啾光纤光栅中电光效应和弹光效应的理论研究

提出了以单轴晶体材料为包层,光轴平行于光栅主轴(z轴)的新型啁啾光纤光栅模型,应用耦合模理论和传输矩阵方法在理论上分析了该类光纤光栅中的电光效应和弹光效应,理论研究发现在包层施加沿光栅轴向的电场和应变场可以改变布拉格波长和反射谱。得到了3种不同单轴晶体为包层时布拉格波长λB和反射光谱随外加电场和应变场变化的曲线。研究结果表明当轴向外加电场从1×107V/m变化到8×107V/m时λB减小0.12nm,当外加应变场从0变化到0.04时,λB减小0.45nm。

Theoretical Study on Electrooptic Effect and Elasto-Optic Effect in Chirped Fiber Grating with Uniaxial Crystal Cladding

A new type of chirped fiber grating with cladding made of uniaxial crystal material whose optical axis is parallel to the axis of grating, i.e., z-axis, is proposed. Electrooptic effect and elasto-optic effect in this kind of fiber gratings are theoretically analyzed based on coupled-mode theory and transfer martrix. It was found that Bragg wavelength _B and the reflective spectra of the chirped grating can be changed by the electric field and the strain applied to the fiber grating cladding along z-axis. The curves of Bragg wavelength _B as a function of an external electric field or the strain are obtained respectively for three kinds of uniaxial crystals as the grating cladding. The calculated results indicate that when the axial electric field applied to the grating cladding varies from 110~7 V/m to 810~7 V/m, _B has the decrease of 0.12 nm, and when the applied strain varies from 0 to 0.04, _B has the decrease of 0.45 nm.