1.College of Electronic and Electrical Engineering, Henan Normal University, Xinxiang 453007, China 2.Key Laboratory of Interfacial Physics Technology Project, Chinese Academy of Sciences, Shanghai 201800, China 3.Key Laboratory Optoelectronic Sensing Integrated Application of Henan Province, Henan Normal University, Xinxiang 453007, China 4.Academician Workstation of Electromagnetic Wave Engineering of Henan Province, Henan Normal University, Xinxiang 453007, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant No. 62075057), Key Laboratory of Interfacial Physics Technology Project, Chinese Academy of Sciences (Grant No. CASKL-IPT2003), Basic Research Project of Key Scientific Research Projects of Higher Education Institutions of Henan Province, China (Grant No. 19B510006), and the Ph. D. Program of Henan Normal University (HNU), China (Grant Nos. gd17167, 5101239170010)
Received Date:14 April 2021
Accepted Date:19 May 2021
Available Online:15 August 2021
Published Online:20 November 2021
Abstract:In this paper, a porous silicon-calcium fluoride hybrid plasmonic waveguide (PS-CaF2 HPW) with an asymmetric silver film is studied. The PS-CaF2 HPW is composed of a PS strip waveguide deposited with asymmetric CaF2 and Ag thin film layers on an SiO2 substrate. In the mid-infrared (MIR) region, the mode characteristics and waveguide sensitivity of the mode in the PS-CaF2 HPW are simulated by using the finite element method (FEM). The results show that there are two fundamental modes (PM 1 and PM 2) with different polarization states in the PS-CaF2 HPW. The real part of the effective refractive index (Re(neff)), transmission loss (α), normalized effective mode field area (A), quality factor (FOM) and sensitivity (Swg) for each of the PM 1 and the PM 2 are studied and optimized. Moreover, the effect of temperature on the performances of the PS-CaF2 HPW is also analyzed. Firstly, the mode field distributions calculated by the FEM indicate that the mode field energy for each of the PM 1 and PM 2 in the PS-CaF2 HPW is mostly restricted to the PS layer and CaF2 layer. Comparing with conventional dielectric waveguides, the mode field energy of the PS-CaF2 HPW is well confined in the PS layer and CaF2 layer. The geometric parameters of the PS-CaF2 HPW are optimized by changing the geometric parameters (W1, W2, and W3). When W1 = 1500 nm, W2 = 300 nm, W3 = 70 nm, and the operating wavelength is ~3.5 μm, α and FOM are 0.019 dB/μm and 1594.99 for the PM 1, and α and FOM are 0.016 dB/μm and 1335.54 for the PM 2, respectively. Secondly, the waveguide sensitivity of the PS-CaF2 HPW is analyzed. The results show that the size of PS layer has a great influence on the waveguide sensitivity. The waveguide sensitivity decreases with the size of the PS layer increasing. In addition, the PS-CaF2 HPW has good temperature resistance. Moreover, temperature has almost no effect on Re(neff), nor α nor A nor FOM nor Swg in a temperature range from -40 K to 40 K. Finally, the fabrication tolerances of the PS-CaF2 HPW are demonstrated, and the good properties are maintained in a size tolerance range from -10 nm to 10 nm. With the advantages in propagation property and loss reduction, the PS-CaF2 HPW provides a feasible label-free biochemical sensing scheme and a method of polarization control devices. Keywords:hybrid plasmonic waveguide/ surface plasmon polaritons/ propagation property/ waveguide sensitivity
全文HTML
--> --> -->
2.波导建模和数值模拟建立非对称银膜PS-CaF2混合等离子体波导的模型, 其三维示意图和二维截面图如图1(a)和图1(b)所示, PS-CaF2 混合等离子体波导由SiO2衬底上的 PS 条状波导、CaF2层和Ag薄膜层组成. PS条形波导的宽度和高度分别为W1 和H1, CaF2和Ag层的右侧壁宽度分别为W2 和W3, 上覆盖层的厚度分别为H2和H3. PS, CaF2和SiO2的折射率分别为2 [29], 1.44和1.45. 波导上覆盖层为待测溶液, 其折射率为nc. 工作波长为3.5 μm时, Ag的介电常数可近似为–86.64+8.74 i [30]. 图 1 非对称银膜的PS-CaF2混合等离子体波导示意图 (a)三维图; (b)波导截面图 Figure1. Schematic diagram of Ag film coated asymmetric PS-CaF2 hybrid plasma waveguide: (a) 3D diagram; (b) cross-sectional view.