Ding Xin, Lin Qiao, Wang Mengjie, Liu Shen, Zhang Weiguan, Chen Nan, Wang Yiping
Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education/Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
Guangdong Laboratory of Artificial Intelligence and Digital Economy (SZ), Shenzhen 518107, China.
Sensors (Basel). 2024 Sep 22;24(18):6118. doi: 10.3390/s24186118.
A novel surface plasmon resonance (SPR) refractive index (RI) sensor based on the D-type dual-mode photonic crystal fiber (PCF) is proposed. The sensor employs a side-polished few-mode PCF that facilitates the transmission of the fundamental and second-order modes, with an integrated microfluidic channel positioned directly above the fiber core. This design minimizes the distance to the analyte and maximizes the interaction between the optical field and the analyte, thereby enhancing the SPR effect and resonance loss for improved sensing performance. Au-TiO dual-layer material was coated on the surface of a microfluidic channel to enhance the penetration depth of the core evanescent field and tune the resonance wavelength to the near-infrared band, meeting the special needs of chemical and biomedical detection fields. The finite element method was utilized to systematically investigate the coupling characteristics between various modes and surface plasmon polariton (SPP) modes, as well as the impact of structural parameters on the sensor performance. The results indicate that the LP mode exhibits greater wavelength sensitivity than the HE mode, with a maximum sensitivity of 33,000 nm/RIU and an average sensitivity of 8272.7 nm/RIU in the RI sensing range of 1.25-1.36, which is higher than the maximum sensitivity of 16,000 nm/RIU and average sensitivity of 5666.7 nm/RIU for the HE mode. It is believed that the proposed PCF-SPR sensor features both high sensitivity and high resolution, which will become a critical device for wide RI detection in mid-infrared fields.
提出了一种基于D型双模光子晶体光纤（PCF）的新型表面等离子体共振（SPR）折射率（RI）传感器。该传感器采用侧面抛光的少模PCF，便于基模和二阶模的传输，其集成微流通道直接位于光纤纤芯上方。这种设计将与分析物的距离最小化，并使光场与分析物之间的相互作用最大化，从而增强SPR效应和共振损耗，以提高传感性能。在微流通道表面涂覆Au-TiO双层材料，以增加纤芯倏逝场的穿透深度，并将共振波长调至近红外波段，满足化学和生物医学检测领域的特殊需求。利用有限元方法系统研究了各种模式与表面等离子体激元（SPP）模式之间的耦合特性，以及结构参数对传感器性能的影响。结果表明，在1.25-1.36的RI传感范围内，LP模式比HE模式表现出更高的波长灵敏度，最大灵敏度为33000 nm/RIU，平均灵敏度为8272.7 nm/RIU，高于HE模式的最大灵敏度16000 nm/RIU和平均灵敏度5666.7 nm/RIU。据信，所提出的PCF-SPR传感器具有高灵敏度和高分辨率，将成为中红外领域宽RI检测的关键器件。
