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报道了圆芯边孔光纤(CSF)中应力分布和双折射的研究结果。用有限元法建立了求解圆芯边孔光纤横截面应力和双折射的计算模型,分析了圆芯边孔光纤横截面应力和应力双折射的分布形态,给出了详尽的物理解释。计算结果表明圆芯边孔光纤的横截面上出现应力分量的拉应力区和压应力区,应力区在纤芯附近对称分布,且不同应力区中应力双折射取向不同。应力分量和应力双折射在圆芯边孔光纤横截面上积分为零。圆芯边孔光纤的几何双折射随波长增加而增大,短波长处几何双折射为零,模式双折射等于应力双折射,随着波长增加,模式双折射逐渐偏离纤芯中心处应力双折射而靠近几何双折射,到长波长处模式双折射主要是几何双折射。对于不同材料组成和结构尺寸的圆芯边孔光纤,模式双折射的数值在10-5量级,随波长增加模式双折射先减小后增加。
The results of studies on stress distribution and birefringence in core-edge fiber (CSF) are reported. The calculation model of cross-section stress and birefringence of optical fiber with round core hole was established by finite element method. The distribution of stress and stress birefringence of optical fiber cross-section of core-hole was analyzed, and a detailed physical explanation was given. The results show that the tensile stress zone and compressive stress zone of the stress component occur in the cross section of the core-side optical fiber. The stress zone is symmetrically distributed near the core and different stress birefringence orientations are different. The stress component and stress birefringence are zero on the fiber cross-section of the core-side aperture. The geometric birefringence increases with the increase of wavelength. The geometric birefringence at short wavelength is zero and the mode birefringence is equal to the stress birefringence. As the wavelength increases, the mode birefringence gradually deviates from the stress birefringence at the center of the core Near geometrical birefringence, mode birefringence at long wavelengths is mainly geometric birefringence. For core-hole optical fiber with different material composition and structure size, the value of mode birefringence is on the order of 10-5. The birefringence first decreases and then increases with increasing wavelength.