在本文中,我们从理论上和实验上研究了双峰干涉传感器的灵敏度,其中在同一物理波导中传播的具有不同属性的两个等离子体激元模式之间发生干涉。与众所周知的马赫-曾德尔干涉(MZI)传感器相比,我们首次表明双模传感器的灵敏度与传感区域长度无关。通过将理论应用于集成的等离子体光子双模传感器来验证这一点,该传感器包括在两个可访问的SU-8光子波导之间共集成的铝(Al)等离子体条纹波导。数值模拟了一系列利用不同长度的等离子体条纹的双峰传感器,显示所有传感器变体的体折射率(RI)灵敏度约为5700nm/RIU,证实了理论结果。理论和数值结果也通过芯片级RI传感实验在三个制造的SU-8/Al双模传感器上进行了实验验证,等离子体传感长度分别为50、75和100μm。发现获得的实验RI灵敏度非常接近,等于4464、4386和4362nm/RIU,分别,确认感测长度对双模传感器灵敏度没有影响。上述结果减轻了设计和光损耗的限制,为更紧凑和强大的传感器铺平道路,可以在超短的传感长度实现高灵敏度值。
In this paper, we study both theoretically and experimentally the sensitivity of bimodal interferometric sensors where interference occurs between two
plasmonic modes with different properties propagating in the same physical waveguide. In contrast to the well-known Mach-Zehnder interferometric (MZI) sensor, we show for the first time that the sensitivity of the bimodal sensor is independent of the sensing area length. This is validated by applying the theory to an integrated plasmo-photonic bimodal sensor that comprises an aluminum (Al)
plasmonic stripe waveguide co-integrated between two accessible SU-8 photonic waveguides. A series of such bimodal sensors utilizing
plasmonic stripes of different lengths were numerically simulated, demonstrating bulk refractive index (RI) sensitivities around 5700 nm/RIU for all sensor variants, confirming the theoretical results. The theoretical and numerical results were also validated experimentally through chip-level RI sensing experiments on three fabricated SU-8/Al bimodal sensors with
plasmonic sensing lengths of 50, 75, and 100 μm. The obtained experimental RI sensitivities were found to be very close and equal to 4464, 4386, and 4362 nm/RIU, respectively, confirming that the sensing length has no effect on the bimodal sensor sensitivity. The above outcome alleviates the design and optical loss constraints, paving the way for more compact and powerful sensors that can achieve high sensitivity values at ultra-short sensing lengths.