Saeidi Parviz, Jakoby Bernhard, Pühringer Gerald, Tortschanoff Andreas, Stocker Gerald, Dubois Florian, Spettel Jasmin, Grille Thomas, Jannesari Reyhaneh
Institute for Microelectronics and Microsensors, Johannes Kepler University, 4040 Linz, Austria.
Silicon Austria Labs GmbH, Europastr. 12, 9524 Villach, Austria.
Sensors (Basel). 2021 Apr 10;21(8):2669. doi: 10.3390/s21082669.
Plasmonic slot waveguides have attracted much attention due to the possibility of high light confinement, although they suffer from relatively high propagation loss originating from the presence of a metal. Although the tightly confined light in a small gap leads to a high confinement factor, which is crucial for sensing applications, the use of plasmonic guiding at the same time results in a low propagation length. Therefore, the consideration of a trade-off between the confinement factor and the propagation length is essential to optimize the waveguide geometries. Using silicon nitride as a platform as one of the most common material systems, we have investigated free-standing and asymmetric gold-based plasmonic slot waveguides designed for sensing applications. A new figure of merit () is introduced to optimize the waveguide geometries for a wavelength of 4.26 µm corresponding to the absorption peak of CO, aiming at the enhancement of the confinement factor and propagation length simultaneously. For the free-standing structure, the achieved is 274.6 corresponding to approximately 42% and 868 µm for confinement factor and propagation length, respectively. The for the asymmetric structure shows a value of 70.1 which corresponds to 36% and 264 µm for confinement factor and propagation length, respectively.
等离子体狭缝波导由于具有高光限制的可能性而备受关注，尽管它们因金属的存在而存在相对较高的传播损耗。虽然在小间隙中紧密限制的光会导致高限制因子，这对于传感应用至关重要，但同时使用等离子体波导会导致传播长度较短。因此，考虑限制因子和传播长度之间的权衡对于优化波导几何结构至关重要。我们以氮化硅作为最常见的材料系统之一的平台，研究了用于传感应用的独立式和非对称金基等离子体狭缝波导。引入了一个新的品质因数（），以针对对应于CO吸收峰的4.26 µm波长优化波导几何结构，旨在同时提高限制因子和传播长度。对于独立式结构，实现的品质因数为274.6，分别对应于约42%的限制因子和868 µm的传播长度。非对称结构的品质因数显示为70.1，分别对应于36%的限制因子和264 µm的传播长度。
