Zekriti M, Nesterenko Dmitry V, Sekkat Z
Appl Opt. 2015 Mar 10;54(8):2151-7. doi: 10.1364/AO.54.002151.
We show, both theoretically and experimentally, that long-range surface plasmons (LRSPs) are supported by asymmetric structure, consisting of a thin silver/gold bilayer metallic film sandwiched between a magnesium fluoride (i.e., MgF) buffer layer and a sensing medium (water). The geometrical parameters of the structure are optimized to yield efficient excitation of LRSPs by using transfer matrix method based on Fresnel reflection. The excitation of LRSPs was performed by using a custom-made automated optical setup based on angular interrogation with the precision of 0.01°. We demonstrate that the bimetallic asymmetric structure achieves better minimum reflectivity resolution than monometallic (gold) asymmetric structure. Finally, figures of merit are compared for bimetallic, monometallic, and conventional SPR structures, and we found that the bimetallic asymmetric structure provides a higher figure of merit; e.g., more than double for monometallic LRSP configuration and 8 times as compared to the conventional surface plasmon resonance sensor.
我们通过理论和实验表明，长程表面等离子体激元（LRSPs）由不对称结构支持，该结构由夹在氟化镁（即MgF）缓冲层和传感介质（水）之间的薄银/金双层金属膜组成。基于菲涅耳反射，使用传输矩阵方法对结构的几何参数进行优化，以实现LRSPs的高效激发。通过使用基于角度询问的定制自动化光学装置进行LRSPs的激发，精度为0.01°。我们证明双金属不对称结构比单金属（金）不对称结构具有更好的最小反射率分辨率。最后，比较了双金属、单金属和传统表面等离子体共振（SPR）结构的品质因数，我们发现双金属不对称结构提供了更高的品质因数；例如，与单金属LRSP配置相比增加了一倍多，与传统表面等离子体共振传感器相比提高了8倍。
