梯度颗粒复合介质的光学双稳

Optical bistability in graded granular composites

重点研究了组分的梯度构形对带壳球形颗粒复合介质的光学双稳特性的影响.其中球形颗粒是由非线性核和介电函数具有梯度分布的线性壳组成.对于壳层介电函数具有幂指数分布的情况,通过求解麦克斯韦方程,得到各区域的势能分布函数,从而求得核内电场的数学表达式.数值研究发现,该复合介质的光学双稳阈值和区域与壳层的厚度及壳层的介电幂指数有关,随着壳层厚度增大或幂指数增大,双稳阈值将变宽.此外,还研究了正入射情况下复合材料体系的反射系数随外电场的变化情况,发现其关系曲线是一条回线.

We studied the intrinsic optical bistability（OB） of coated spherical particles with graded dielectric profiles. According to Maxwell equations, we obtained the spatial average of the local field in the core as a function of the external applied field. Numerical results for power-law graded profiles show that the optical bistable behavior is dependent on the shell thickness and the power-laws exponent k. The interval of optical bistability increases with increasing shell thickness or increasing k. In addition, the field-dependent reflectance at normal incidence R in random composites is also investigated, and a hysteretic loop is observed.