用数值分析方法研究了对称轴两侧光场具有相位跃变的暗条纹在具有光致异构非线性的聚合物中的演化情况及一些有关性质.结果表明,两侧光场相位跃变不为π时,入射暗条纹会向两边分开而形成Y型分裂;相位跃变从0到π增大,分裂程度变小.发现相位超前一边分出来的灰条纹与原传播方向之间的夹角对于不同相位跃变值基本保持不变,而相位滞后一边分出来的灰条纹与原传播方向之间的夹角则随相位跃变的增大而减小;相同相位跃变、不同光强的光束分开角度基本保持不变.数值模拟发现这种Y型分裂在材料中产生的折射率改变具有波导作用,可以使入射高斯光束产生Y型分裂. The evolution of the dark stripe with phase jump in the optical field on both sides of the symmetry axis and some related properties have been studied by means of numerical analysis. The results show that the phase transition of the optical field on both sides is not Is π, the incident dark stripe will be separated from the two sides to form a Y-type splitting; the phase jump increases from 0 to π, the degree of splitting becomes smaller.It is found that the angle between the gray stripe and the original propagation direction For different phase jump values ​​remain unchanged, while the phase lag out of the edge of the gray stripes and the original propagation angle with the phase transition increases with the decrease; the same phase jump, different light intensity The separation angle of the beam remained basically unchanged.Numerical simulation found that the refractive index change induced by the Y-split in the material has a waveguide effect and can cause the Y-splitting of the incident Gaussian beam.