Abstract. A hybrid plasmon waveguide (HPWG) consisting of a gold layer, a 100-nm high nanogap, and a SiN layer with a high refractive index on a SiO2 / Si substrate was designed by simulation and was applied in a Mach–Zehnder interferometer biosensor. For the incidence of a transverse magnetic (TM) mode light, a strongly enhanced electric field in the nanogap region caused by the modified surface plasmon enabled highly sensitive detection at the metal/solution interface. In contrast, the transverse electric (TE) mode enabled a high bulk-sensitivity due to the evanescent field in the nanogap. The HPWG structure was formed by electron beam lithography and electrochemical sacrificial layer etching. The output intensity of the fabricated device oscillated upon the replacement of the medium in the nanogap for both TE and TM mode excitations, which agreed with the obtained simulation results. Furthermore, the hybridization of DNA on the gold surface was detected, demonstrating that the HPWG structure is applicable to use in biosensing.

中文翻译：

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用于高灵敏度生物传感的混合等离子体波导

摘要。通过模拟设计了由金层、100 nm 高纳米间隙和高折射率 SiN 层组成的混合等离子体波导 (HPWG)，该层位于 SiO2/Si 衬底上，并应用于 Mach-Zehnder 干涉仪生物传感器。对于横向磁 (TM) 模式光的入射，由改性表面等离子体激元引起的纳米间隙区域中的强增强电场能够在金属/溶液界面进行高灵敏度检测。相比之下，由于纳米间隙中的倏逝场，横向电 (TE) 模式实现了高体积灵敏度。HPWG 结构是通过电子束光刻和电化学牺牲层蚀刻形成的。对于 TE 和 TM 模式激发，在更换纳米间隙中的介质时，制造的器件的输出强度发生振荡，与得到的模拟结果一致。此外，检测到金表面上的 DNA 杂交，证明 HPWG 结构适用于生物传感。