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对两组份非线性复合材料的光学非线性性质的临界行为进行了研究。考虑第一组份为非线性材料 ,其电流、电压间服从I=g1V +χ1Vβ 关系 ;而第二组份为线性材料 ,电流、电压间满足I=g2 V ,其中g1,χ1是第一组份的线性电导和光学非线性极化率 ,g2 是第二组份的线性电导 ,β是第一组份材料的光学非线性指数。分别采用了有效介质近似和相对电阻涨落的标度理论两种方法计算了系统有效响应的临界指数随光学非线性指数及维数的变化规律。用不同的方法得到系统的有效线性电导ge 和有效光学非线性极化率 χe(β)的临界指数M(β)和N(β)的结论也不同。有效介质近似得到M(β) =1和N(β) =(β+1) / 2 ,即M(β)与 β和d都无关 ,而N(β)只与有 β关而与d无关 ;而相对电阻涨落标度理论方法得到的M(β)和N(β)与 β和d都有关。
The critical nonlinear optical behavior of two component nonlinear composites was studied. Considering that the first component is a nonlinear material, the current and voltage follow the relation of I = g1V + χ1Vβ; the second component is a linear material, and the current and voltage satisfy I = g2 V, where g1 and χ1 are the first group Part linear conductivity and optical nonlinear polarizability, g2 is the linear conductance of the second component, and β is the optical nonlinear index of the first component material. Two methods, the effective medium approximation and the scaling theory of relative resistance fluctuation, respectively, are used to calculate the variation law of the critical exponent of the effective response of the system with the optical nonlinear exponent and dimension. The conclusions of the critical exponent M (β) and N (β) of the effective linear conductivity ge and the effective optical nonlinear polarizability χe (β) obtained by different methods are also different. The effective medium is approximated by M (β) = 1 and N (β) = (β + 1) / 2, ie M (β) is independent of β and d, while N ; And M (β) and N (β) obtained by the theory of relative resistance fluctuation scale are related to both β and d.