Research on Pohotonic Crystal Fiber Sensors Based on SPR Effect—D-Type Pohotonic Crystal Fiber

光子晶体光纤(Pohotonic Crystal Fiber, PCF)作为一种新型的光纤传感结构，在光纤通信等领域展示了其重要的应用价值。其独特的周期性结构设计能够有效调控光的传播特性，打破了传统光纤在纤芯尺寸、折射率均匀性等基本参数上的限制，从而实现了超高的光传播效率和优异的非线性性能，为高功率光纤激光器、超连续光源等关键领域提供了理想的光学平台。PCF的光学特性和高性能源于其严格的结构设计，这种周期性的微型结构使其具备了强大的波导效应和色散控制能力。然而，由于PCF的复杂结构特性决定了其光学性能对其结构参数具有高度敏感性，因此直接通过实验手段制备不同结构的PCF并进行性能测试已不具备高效性和普适性。这种方法不仅耗时费力，难以全面探究PCF结构参数与光学性能之间的内在关系，且容易陷入局部最优而忽视全局优化的困境。因此，研究者必须建立科学的理论模型和数值仿真方法，通过计算机辅助设计和计算模拟来系统分析PCF在不同背景材料、空气孔分布特征、空气孔尺寸和孔间距等关键参数下的光学性能演变规律。基于表面等离子体共振(Surface Plasmon Resonance, SPR)效应，本文设计了一种高灵敏度的D型光子晶体光纤传感器，其由上下两个大空气孔和左右两个小空气孔组成纤芯，并在纤芯左右两边设计两个更大的空气孔来加强传感性能。首先对传感器的模场进行分析，交代了基模和SPP模在发生共振时的关系，并展示了发生SPR现象时的损耗谱，其次讨论了不同结构参数对传感性能的影响，主要讨论了金属膜的厚度和金属膜的材料对传感性能的影响，确定了最优的参数，得到了在1.36~1.40的检测范围内，灵敏度为6110 nm/RIU，分辨率为1.6367 × 10−5 RIU的D型PCF-SPR传感器。Pohotonic Crystal Fibre, PCF serves as a novel type of optical fibre structure to show significant technical advantages in the field of optical communication. To its unique periodic structural design serves to effectively control the propagation characteristics of light, thus achieving ultra-high efficiency in light propagation and also possessing excellent nonlinear performance, which provide an ideal optical platform for key fields such as high-power laser fibre lasers, super-continuum light sources, etc. The optical characteristics of PCFs are fundamentally due to their precise structural designs. This periodic microstructure imparts PCFs with robust wave guiding effects and advanced dispersion control capabilities. However, due to the complex structural characteristics of PCFs, their optical performance is highly sensitive to specificstructural parameters. Achieving this through conventional experimental methods is not efficient or universal. This approach is not only time-consuming and resource-intensive, making it difficult to comprehensively investigate the intrinsic relationships between PCF structural parameters and their optical performance, and it often leads to local optimizations at the expense of overlooking broader global optimizations. Achieving this requires establishing robust theoretical models and numerical simulation methodologies, supported by computer-aided design and computational simulations, to systematically analyze the optical performance evolution of PCFs under various key parameters such as background materials, air hole distribution characteristics, air hole dimensions, and inter-pore spacing Based on the surface plasmon resonance (SPR) effect, this article designs a high-sensitivity D-type pohotonic crystal fiber (PCF) sensor was designed, which is composed of two large air holes on the top and bottom and two small air holes on the left and right. Additional larger air holes were strategically placed on both sides of the fiber core to enhance sensing performance. Firstly, a detailed analysis of the mode field in the sensor was conducted. This analysis provided insights into the relationship between the base mode and surface plasmon resonance (SPR) mode during resonance, while demonstrating the loss spectrum at the occurrence of the SPR phenomenon. Subsequently, an extensive discussion on the impact of various structural parameters on sensing performance was carried out. The primary focus was on how the thickness and material choice of the metal layer affect the sensor’s sensitivity and resolution. Optimal parameters were identified through this analysis. As a result, in the detection range spanning from 1.36 to 1.40 RIU (Refractive Index Units), the D-type PCF-SPR sensor achieved an impressive sensitivity of 6110 nm/RIU with a resolution of 1.6367 × 10−5 RIU, showcasing its high performance and reliability in sensing applications.