Opt Lett. 2023 Jul 1;48(13):3375-3378. doi: 10.1364/OL.493937.
We experimentally demonstrated polarization multiplexing schemes in a tilted fiber grating (TFBG) to achieve polarization-independent fiber-optic surface plasmon resonance (SPR) sensors. The first used two orthogonal polarized lights separated by a polarization beam splitter (PBS) that are p-polarized in polarization-maintaining fiber (PMF) and precisely aligned with the tilted grating plane, so as to achieve the transmission of p-polarized light in two opposite directions of the Au-coated TFBG to excite SPR. Alternatively, polarization multiplexing was also achieved by exploring two polarization components to achieve the SPR effect through a Faraday rotator mirror (FRM). The SPR reflection spectra are polarization-independent of the light source and any perturbations to fibers, which are explained by the superposition of p- and s-polarized transmission spectra in equal proportions. The spectrum optimization is presented to reduce the proportion of the s-polarization component. A polarization-independent TFBG-based SPR refractive index (RI) sensor with a wavelength sensitivity of 555.14 nm/RIU and an amplitude sensitivity of 1724.92 dB/RIU for small changes is obtained, exhibiting unique advantages of minimizing the polarization alterations by mechanical perturbations.
我们在倾斜光纤光栅（TFBG）中实验演示了偏振复用方案，以实现偏振无关的光纤表面等离子体共振（SPR）传感器。第一种方案使用了两个由偏振分束器（PBS）分离的正交偏振光，它们在保偏光纤（PMF）中是 p 偏振的，并与倾斜光栅平面精确对准，从而实现了 Au 涂层 TFBG 两个相反方向上的 p 偏振光传输，以激发 SPR。或者，也可以通过探索两个偏振分量来实现偏振复用，通过法拉第旋转镜（FRM）实现 SPR 效应。SPR 反射谱对光源和光纤的任何扰动都是偏振无关的，这可以通过 p 偏振和 s 偏振透射谱的等比例叠加来解释。提出了光谱优化来降低 s 偏振分量的比例。获得了一种基于偏振无关 TFBG 的 SPR 折射率（RI）传感器，其波长灵敏度为 555.14 nm/RIU，对于小的折射率变化，其幅度灵敏度为 1724.92 dB/RIU，具有最小化机械扰动引起的偏振变化的独特优势。
