Sherif Sherif M, Swillam Mohamed A
Department of Physics, School of Science and Engineering, The American University in Cairo, Cairo, 11835, Egypt.
Sci Rep. 2023 Jul 29;13(1):12311. doi: 10.1038/s41598-023-38926-9.
Sensing in the mid infrared spectral range is highly desirable for the detection and monitoring of different gases. We hereby propose a CMOS compatible silicon-based sensor that operates at (3.5-10 μm) within the mid infrared range. The silicon material is doped to the level that shifts its plasmonic resonance to 3 μm wavelength. The sensor device comprises an in-line rectangular microcavity and a stub microcavity resonator. The resonance frequencies/wavelengths of the two resonators were studied with different design dimensions. When the two resonators are designed to resonate at close frequencies, the interesting Fano resonance with its distinct and sharp line shape is excited due to the interference between the two resonance profiles. Fano resonance is useful for highly sensitive measurements due to its abrupt intensity changing profile. The sensor is studied and analyzed using Finite Difference Element and 2D Finite Difference Time Domain methods. The sensor's performance is characterized by its high sensitivity of 6000 nm/RIU, FOM of 353, and limited insertion loss of 0.45 dB around 6.5 μm operation wavelength. Furthermore, we develop the sensor for simultaneously detecting formaldehyde CHO and nitrous oxide NO gases from their strong absorption bands at 3.6 μm and 4.46 μm wavelengths, respectively.
在中红外光谱范围内进行传感对于不同气体的检测和监测非常有必要。我们在此提出一种与CMOS兼容的硅基传感器，其在中红外范围内（3.5 - 10μm）工作。硅材料被掺杂到使其等离子体共振波长移至3μm的水平。该传感器器件包括一个 inline 矩形微腔和一个短截线微腔谐振器。研究了两种谐振器在不同设计尺寸下的谐振频率/波长。当两个谐振器被设计为在相近频率下谐振时，由于两个谐振谱之间的干涉，会激发具有独特尖锐线形的有趣的法诺共振。法诺共振因其急剧的强度变化曲线而对高灵敏度测量很有用。使用有限差分元法和二维有限差分时域法对该传感器进行了研究和分析。该传感器的性能表现为在6.5μm工作波长附近具有6000nm/RIU的高灵敏度、353的品质因数以及0.45dB的有限插入损耗。此外，我们开发该传感器用于分别从甲醛CHO和一氧化二氮NO在3.6μm和4.46μm波长处的强吸收带同时检测这两种气体。
