Plasmonic Non-linear Surface Relief Nano-structures in Azobenzene-Containing Materials and Their Applications

含偶氮苯材料中的等离子体非线性表面起伏纳米结构及其应用

• 批准号: RGPIN-2015-05743
• 负责人: Sabat, RibalGeorges
• 金额: $ 1.6万
• 依托单位: Royal Military College of Canada
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=678839
• 关键词: Plasmonic; Non; linear; Surface; Relief

Holographic nanostructures can be photo-induced as surface-relief in azobenzene-containing solid thin-films due to the reversible trans-cis photo-isomerization of the azobenzene chromophores. In the simplest case, linear surface-relief diffraction gratings are inscribed on azo thin-films upon exposure to a collimated laser interference pattern. The inscription of nanostructures on azo films can be done in a few minutes and consists of a single fabrication step. This makes them highly advantageous compared to other nanofabrication techniques. The resulting nanostructures are stable over time and can be coated with other materials, depending on the application. My group has recently developed new experimental techniques to inscribe non-linear surface-relief structures on azo films. For example, we successfully inscribed holographic representations of cylindrical and spherical lenses as chirped-pitch diffraction gratings. These gratings focalized a probing light beam just like a real physical lens. We also designed and fabricated a novel conical fixture that enabled the production of both constant-pitch and chirped-pitch circular surface-relief gratings. Upon coating these novel non-linear nanostructures with a thin metallic layer, surface plasmons could be generated. These plasmons are resonant electromagnetic waves that propagate at the boundary between the metal layer and an adjacent dielectric medium. Upon excitation of the plasmon, the local electromagnetic fields at the boundary are highly amplified. These fields could extend up to 200 nanometers above and below the interface and this results in light entrapment and enhanced transmission throughout the dielectric layer. Surface plasmons are normally generated if several parameters are simultaneously satisfied. This allows them to be equally used as sensors. The objective of this proposal is to study and optimize the generation of surface plasmons in those novel non-linear nanostructures which where inscribed on azo thin-films. We will study the various parameters required to excite the strongest plasmons in circular gratings. We will also optimize the chirped-pitch gratings for optimal light bandwidth excitations, as well as utilize them as plasmonic energy concentrators. These gratings will be incorporated in thin-film solar cells and organic light emitting diodes, which will act as the dielectric media. The goal is to achieve substantial and controllable surface plasmon enhancements over a wide light bandwidth as well as in all light polarizations. This will be done by methodical studies on the nanostructures' shape and their influence on the plasmon excitation. These nanostructures will also be studied for their potential use in sensing applications, particularly biosensors.

由于偶氮苯发色团的可逆的反-顺光异构化作用，在含偶氮苯的固体薄膜中可以光诱导形成全息纳米结构。在最简单的情况下，线性表面浮雕衍射光栅刻在偶氮薄膜曝光后，准直激光干涉图案。在偶氮薄膜上的纳米结构的铭文可以在几分钟内完成，并且由单个制造步骤组成。这使得它们与其他纳米纤维技术相比非常有利。所得纳米结构随时间推移而稳定，并且可以根据应用涂覆其他材料。我的小组最近开发了新的实验技术，在偶氮薄膜上刻划非线性表面浮雕结构。例如，我们成功地将柱面透镜和球面透镜的全息表示刻为啁啾间距衍射光栅。这些光栅就像一个真实的物理透镜一样聚焦探测光束。我们还设计和制造了一种新型的锥形夹具，使生产的恒定间距和啁啾间距的圆形表面浮雕光栅。在用薄金属层涂覆这些新颖的非线性纳米结构时，可以产生表面等离子体。这些等离子体激元是在金属层和相邻电介质之间的边界处传播的谐振电磁波。在激发等离子体激元时，边界处的局部电磁场被高度放大。这些场可以在界面上方和下方延伸高达200纳米，这导致光截留和整个介电层的增强透射。如果同时满足几个参数，通常会产生表面等离子体。这使得它们同样可以用作传感器。本论文的目的是研究和优化那些刻在偶氮薄膜上的新型非线性纳米结构的表面等离子体激元的产生。我们将研究在圆光栅中激发最强等离子体所需的各种参数。我们还将优化啁啾间距光栅的最佳光带宽激发，以及利用它们作为等离子体能量集中器。这些光栅将被纳入薄膜太阳能电池和有机发光二极管，这将作为介电介质。我们的目标是实现大量的和可控的表面等离子体增强在宽的光带宽，以及在所有的光偏振。这将通过对纳米结构的形状及其对等离子体激元激发的影响的系统研究来完成。这些纳米结构也将研究其在传感应用，特别是生物传感器中的潜在用途。