A novel long-period fiber grating (LPFG) with a four-layer structure is proposed, made by coating double layers of both ZnO and Ag onto a bare LPFG. Pulsed laser deposition (PLD) technology can effectively control the flatness and nanoscale thickness of ZnO film, which is conducive to achieving full energy coupling with the Ag layer and the grating. Compared with SiO₂, ZnO has a higher thermal expansion coefficient and refractive index, which ensures that coated LPFG has a higher temperature sensitivity. As the fourth layer of the structure, colloidal silver is coated onto the surface of the ZnO film at an optimal thickness by a spin-coating method. The higher thermal expansion coefficient of the Ag film and a plasma resonance effect on its surface cause the temperature sensitivity to increase again. The sensitivity of the coated Ag-ZnO-LPFG structure is 1.4 times higher than that of the bare fiber. The temperature sensitivity is increased from 0.063 nm C⁻¹ to 0.088 nm C⁻¹, while retaining good linearity. We also solve the problem whereby the coating disturbs the coupled-wavelength transmittance, and by doing so, we increase the stability of the coupled-wavelength transmittance and enhance measurement accuracy.

提出了一种新颖的具有四层结构的长周期光纤光栅（LPFG），该方法是将ZnO和Ag的双层涂层涂覆到裸露的LPFG上。脉冲激光沉积（PLD）技术可以有效地控制ZnO膜的平整度和纳米级厚度，这有利于实现与Ag层和光栅的完全能量耦合。与SiO _2比较，ZnO具有较高的热膨胀系数和折射率，从而确保涂覆的LPFG具有较高的温度敏感性。作为结构的第四层，通过旋涂法将胶体银以最佳厚度涂覆在ZnO膜的表面上。Ag膜的较高的热膨胀系数和在其表面上的等离子体共振效应导致温度敏感性再次增加。包覆的Ag-ZnO-LPFG结构的灵敏度是裸光纤的1.4倍。温度灵敏度从0.063 nm C ^-1增加到0.088 nm C ^-1，同时保持良好的线性度。我们还解决了涂层干扰耦合波长透射率的问题，通过这样做，我们提高了耦合波长透射率的稳定性并提高了测量精度。