School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
Science. 2013 Apr 19;340(6130):331-4. doi: 10.1126/science.1233746.
Light can be coupled into propagating electromagnetic surface waves at a metal-dielectric interface known as surface plasmon polaritons (SPPs). This process has traditionally faced challenges in the polarization sensitivity of the coupling efficiency and in controlling the directionality of the SPPs. We designed and demonstrated plasmonic couplers that overcome these limits using polarization-sensitive apertures in a gold film. Our devices enable polarization-controlled tunable directional coupling with polarization-invariant total conversion efficiency and preserve the incident polarization information. Both bidirectional and unidirectional launching of SPPs are demonstrated. The design is further applied to circular structures that create radially convergent and divergent SPPs, illustrating that this concept can be extended to a broad range of applications.
光可以被耦合到金属-电介质界面上的传播电磁波表面波中，这种波被称为表面等离激元（SPP）。在耦合效率的偏振灵敏度和控制 SPP 方向上，这一过程一直面临挑战。我们设计并展示了使用金膜中的偏振敏感孔径克服这些限制的等离子体耦合器。我们的器件使用偏振敏感孔径实现了偏振控制可调谐的定向耦合，具有偏振不变的总转换效率，并保留了入射偏振信息。我们演示了 SPP 的双向和单向发射。该设计进一步应用于圆形结构，产生了径向会聚和发散的 SPP，表明该概念可以扩展到广泛的应用领域。
