基于表面等离激元的偏振态控制光开关

利用四个Au纳米棒组成的类矩形纳米棒四聚体结构设计了一种基于偏振态控制的光开关,并采用有限元法研究了该结构对入射光偏振态的响应特性.研究发现,该结构的透射光谱对入射光的偏振方向具有很强的依赖性,当入射光的偏振角度变化π/2时,其特征峰的开关比分别能达到27.81dB和21.65dB.分析表明,该结构的开关效应主要由不同偏振态下所导致的水平双纳米棒和竖直双纳米棒之间的近场耦合强度不同而实现,该结构透射系数与偏振角度的关系服从Malus law.此外,通过改变类矩形纳米棒阵列结构参数,研究了结构参数对其光开关响应特性的影响.在此基础上,通过改变阵列的周期参数,研究了入射光水平偏振和垂直偏振下周期参数对单元结构透射光谱的影响.该研究结果能够为可调谐双波长偏振光开关的设计提供理论依据.

Polarization-controlled Optical Switch Based on Surface Plasmon

An optical switch based on polarization state control is designed by using a rectangular-like nanorods tetramer composed of four Au nanorods.The finite element method is used to study the response characteristics of the structure to incident light polarization.It is found that the transmission spectrum of the structure dependent strongly on the polarization direction of the incident light.When the polarization angle of the incident light changes byπ/2,the switching ratio of the characteristic peaks can reach 27.81 dB and 21.65 dB,respectively.The analysis shows that the switching effect is mainly caused by the different near-field coupling strength between the horizontal double rod and the vertical double rod at the different polarization states.The relationship between the transmittance and the polarization angle of the structure obeys the Malus law.In addition,the influence of structural parameters on the response characteristics of optical switches is studied by changing the structural parameters of the rectangular-like nanorod array.On this basis,the influence of the periodic parameters on the transmission spectrum of the unit structure under the horizontal and vertical polarization of the incidence light is studied by changing the period parameters of the array.These results can provide a theoretical basis for the design of tunable dual-wavelength polarization-controlled optical switch.