In this paper, for enhancement of the nonlinear optical properties of photorefractive gain, a novel plasmonic waveguide is proposed. The geometry of the proposed structure is optimized to reach the highest photorefractive gain. The proposed structure is based on bimetallic structure and it includes a graphene layer. It is shown that a strong mode can be coupled to a weak mode by means of photorefractive effect. It is found that comparing with the conventional symmetric and asymmetric metal-insulator-metal plasmonic waveguides, the proposed structure with different metals and a graphene layer with an optimized notch has higher photorefractive gain and longer propagation distance, the distance for which a net photorefractive gain exists. The effect of the crystal thickness and amplitude inputs are also analyzed. It is found that there is an optimum crystal thickness that yields the maximum photorefractive gain.

在本文中，为了增强光折变增益的非线性光学特性，提出了一种新型等离子体波导。所提出结构的几何形状经过优化以达到最高的光折变增益。所提出的结构基于双金属结构，它包括石墨烯层。结果表明，强模式可以通过光折变效应耦合到弱模式。结果表明，与传统的对称和非对称金属-绝缘体-金属等离子体波导相比，所提出的具有不同金属和具有优化凹口的石墨烯层的结构具有更高的光折变增益和更长的传播距离，净光折变增益为存在。还分析了晶体厚度和幅度输入的影响。