Zhou Chuanhong, Kohli Punit
J Appl Phys. 2011 May 1;109(9):93114-931146. doi: 10.1063/1.3582005. Epub 2011 May 12.
An ultracompact plasmonic beam splitter is theoretically and numerically investigated. The splitter consists of a V-shaped nanoslit in metal films. Two groups of nanoscale metallic grooves inside the slit (A) and at the small slit opening (B) are investigated. We show that there are two energy channels guiding light out by the splitter: the optical and the plasmonic channels. Groove A is used to couple incident light into the plasmonic channel. Groove B functions as a plasmonic scatter. We demonstrate that the energy transfer through plasmonic path is dominant in the beam splitter. We find that more than four times the energy is transferred by the plasmonic channel using structures A and B. We show that the plasmonic waves scattered by B can be converted into light waves. These light waves redistribute the transmitted energy through interference with the field transmitted from the nanoslit. Therefore, different beam splitting effects are achieved by simply changing the interference conditions between the scattered waves and the transmitted waves. The impact of the width and height of groove B are also investigated. It is found that the plasmonic scattering of B is changed into light scattering with increase of the width and the height of B. These devices have potential applications in optical sampling, signal processing, and integrated optical circuits.
对一种超紧凑型等离子体光束分离器进行了理论和数值研究。该分离器由金属薄膜中的V形纳米狭缝组成。研究了狭缝内部（A）和小狭缝开口处（B）的两组纳米级金属凹槽。我们表明，有两个能量通道引导光从分离器射出：光学通道和等离子体通道。凹槽A用于将入射光耦合到等离子体通道中。凹槽B起到等离子体散射体的作用。我们证明，在光束分离器中，通过等离子体路径的能量转移占主导地位。我们发现，使用结构A和B时，通过等离子体通道转移的能量超过四倍。我们表明，由B散射的等离子体波可以转换为光波。这些光波通过与从纳米狭缝传输的场发生干涉来重新分配传输的能量。因此，通过简单地改变散射波和传输波之间的干涉条件，可以实现不同的光束分裂效果。还研究了凹槽B的宽度和高度的影响。发现随着B的宽度和高度的增加，B的等离子体散射转变为光散射。这些器件在光学采样、信号处理和集成光学电路中具有潜在应用。
