环形腔微光纤MZI的海水温/盐度同时测量的设计与模拟

为实现海水中温度和盐度(温/盐度)同时测量,设 计了一种环形腔微光纤Mach-Zehnder干涉仪(MZI)。首先,计算了MZI在不同温/盐度下的 输出光谱,光谱中同时存在谐 振峰和干涉峰,分别由环形腔谐振和MZ干涉引起,由于谐振峰和干涉峰对温/盐度变化的响 应不同,因而 可将其运用于海水的温/盐度同时测量；其次,为了提升MZI的测量灵敏度,计算了灵敏度 与 其结构参数的关系。结果表明,谐振峰的温/盐度灵敏度只与制成环形腔的微光纤直径有关 ,而干涉峰灵敏 度同时与MZI两个微光纤臂的直径和长度相关,当制成环形腔的微光纤臂是MZI两臂中直径 较 小且长度较大的一臂时,能得到较高的测量灵敏度。经过优化后,干涉峰的温/盐度灵 敏度比传统的 光纤光栅分别提升了75倍和约3650倍。本文 设计的MZI具有结构简单、灵敏度高的优点,可为研制新型的海洋微光纤传感器提供参考。

Design and simulation of knot resonator-coupled microfiber MZI for simultaneous measurement of seawater temperature and salinity

In this paper,the knot resonator-coupled microfiber Mach-Zehnder interferomete r (MZI) is proposed,and the dependence of temperature and salinity sensitivities on its structure parameters is calculated.The transmission spectra at different temperatures and salinities are calculated, and the resonant dip and the interference dip appear together in the spect ra,resulting from resonance and interference,respectively.The resonant dip an d interference dip have different responses to the changes of temperature and salinity,and thus can be used to simultaneously measure temperature and salinity of seawater.Resu lts show that the sensitivity of resonant dip is only related to the microfiber diameter of knot resonator,while the sensitivity of interference dip is related to the two microfiber diameters and lengths of MZI. When the microfiber fabricating the knot resonator is the thinner and longe r one between the two microfibers of MZI,high sensitivities can be obtained.Compared with traditional fiber Bragg gratings,the temperature and salinities sensitivity of i nterference dip improve by 75times and about 3650times after optimizati on,respectively.The proposed interferometer shows the advantages of simple structure and high sensitivity, and may offer theoretical basis for development of marine microfiber sensors.