Ultrasmooth Gold Nanogroove Arrays: Ultranarrow Plasmon Resonators with Linewidth down to 2 nm and Their Applications in Refractive Index Sensing
Ultrasmooth Gold Nanogroove Arrays: Ultranarrow Plasmon Resonators with Linewidth down to 2 nm and Their Applications in Refractive Index Sensing
复制标题
超光滑金纳米槽阵列：线宽低至 2 nm 的超窄等离子体谐振器及其在折射率传感中的应用
DOI：
10.1002/adfm.202108741
复制
发表时间：
2021-11-25
影响因子：
19
通讯作者：
Jin，Chongjun
中科院分区：
文献类型：
--
作者：
Shen，Yang;He，Kai;Jin，Chongjun
等离子体纳米结构在许多应用中提供了诱人的前景，从激光到生物传感，由于其无与伦比的光浓度超过衍射极限。然而，这一前景被金属固有的高损耗大大削弱。在这里，实验超高Q等离子体共振的线宽下降到2 nm（Q-因子为350）和共振强度的51%，在超光滑的金纳米槽阵列的报告。这种实验性的超窄共振来自两个关键因素。首先，Fabry-Pérot和Wood异常模式之间的几何诱导耦合显著抑制了凹槽阵列的辐射阻尼。其次，超光滑的金表面制作的模板剥离最大限度地减少其表面散射和晶界散射。受益于这种超窄谐振，在正常入射检测下折射率（RI）感测中的284的品质因数（FOM）和617的FOM* 被证明，前者是所有报道的宽RI范围等离子体RI传感器中的记录FOM。该阵列进一步被证明是用于检测巯基羧酸的表面厚度传感器，其表面灵敏度为0.18 nm/CH 2，这表明该阵列是用于表面分析物的厚度检测和无标记生物医学传感的有前途的平台。
Plasmonic nanostructures offer an enticing prospect in many applications, ranging from lasing to biosensing, due to their unrivaled light concentration beyond the diffraction limit. However, this promise is substantially undercut by the intrinsically high losses in metals. Here, an experimental ultra‐high‐Q plasmon resonance with a linewidth down to 2 nm (Q‐factor ≈ 350) and a resonance intensity of 51% in an ultrasmooth gold nanogroove array is reported. Such an experimental ultranarrow resonance arises from two key factors. First, a geometrical‐induced coupling between the Fabry–Pérot and Wood's anomaly modes significantly suppresses the groove array's radiative damping. Second, an ultrasmooth gold surface fabricated by template stripping minimizes its surface scattering and grain boundary scattering. Benefiting from this ultranarrow resonance, a figure of merit (FOM) of 284 and an FOM* of 617 in refraction index (RI) sensing under normally incident detection are demonstrated, the former of which is the record FOM in all reported broad‐RI‐range plasmonic RI sensors. The array is further demonstrated as a surface thickness sensor for detecting mercaptocarboxylic acids with the surface sensitivity of 0.18 nm/CH2, which suggests that the array is a promising platform for thickness detection of surface analytes and label‐free biomedical sensing.