光纤端面微型传感单元的共振模式及影响因素

Resonance Modes and Influencing Factors of Micro Sensing Unit on Fiber End Face

首先在光纤端面设计一种由金光栅-介质-金薄膜构成的复合结构,并研究多种共振模式随介质层厚度的变化及其场分布特点。然后研究限制在金光栅和金薄膜纳米级间距的波导共振模,通过反射谱的变化和谐振模式的电场分布特点研究不同阶次的纳米谐振效应。此外,还仿真计算金光栅的宽度、厚度及周期、中间介质层折射率和金反射薄膜厚度的变化对纳米谐振腔光谱特性的影响,根据波导模干涉的相位差公式定性分析其谐振频率的变化,并计算获得纳米谐振腔对腔内介质折射率和腔长的灵敏度。最后,搭建微位移平台,验证光纤端面与金薄膜所构成的Fabry-Perot干涉光谱随间距的变化,并提出光纤端面纳米谐振结构的实现方案。

First, a composite structure composed of gold grating, medium, and gold film is designed on the end face of optical fiber, and the variation of various resonance modes with the thickness of medium layer and their field distribution characteristics are studied. Then, the waveguide resonant modes limited to the nanometer spacing between the gold grating and the gold film are studied. The different order of nanometer resonance effects are studied by the variation of the reflection spectrum and the electric field distribution characteristics of the resonant mode. In addition, the simulation calculation of gold grating width, thickness, and cycle, intermediate medium layer refractive index and thickness of gold film changes on the spectral characteristics and the effect of nano-resonator based on waveguide mode interference phase difference formula of the qualitative analysis of the change of resonance frequency, and calculate the obtained nano-cavity on the sensitivity of the refractive index and the length of cavity medium. Finally, a micro-displacement platform is built to verify the Fabry-Perot interference formed spectrum with the distance between the optical fiber end face and the gold film, and the realization scheme of the optical fiber end face nano-resonance structure is proposed.