液体环境中微纳光纤布拉格光栅的温度特性

Temperature Characteristics of Micro-Nanofiber Bragg Grating Surrounded with Liquids

针对微纳光纤布拉格光栅(MNFBG)在应用中存在的温度依赖问题,数值模拟了被不同折射率液体包围的MNFBG的反射波长与温度的关系,并且制作了可更换封装液体的MNFBG用于实验研究。通过使用蒸馏水和不同折射率的匹配液封装MNFBG,得到了MNFBG反射光谱及其中心波长随封装液体温度的变化规律。研究发现,在相同的温度变化过程中,不同性质的封装液体会影响MNFBG反射光谱的形状和移动方向,改变了普通光纤布拉格光栅(FBG)在温度升高过程中反射光谱形状几乎不变但其中心波长线性红移的特性。封装液体的折射率和热光系数越大,MNFBG反射波长随温度的变化越趋于非线性。换用折射率和热光系数分别为1.456和4×10^(-4)℃^(-1)的匹配液体后,MNFBG反射波长的温度灵敏度为-50.3pm/℃。MNFBG特性与环境液体、温度和FBG的尺寸有关,通过有效控制相关因素可以实现FBG在更多领域的功能化应用。

In order to investigate the temperature dependence of micro-nanofiber Bragg grating （MNFBG） in application, we simulate the relationship between reflection wavelength and temperature of MNFBG which is surrounded with liquids with different refractive indexes, and MNFBGs surrounded with replaceable encapsulating liquids are fabricated and used in experiments. In experiments, the variations in reflection spectral and its center wavelength with temperature of encapsulating liquids can be obtained when we encapsulate the MNFBG with distilled water and matching liquids with different reflective indexes. Research results show that the shape and the moving direction o{ reflection spectra can be ef^ected by the encapsulating liquids with different properties in the same temperature changing process, which is different from the ordinary fiber Bragg grating （FBG）. The reflection spectral shape of the ordinary FBG almost does not change when temperature is increasing, but its center wavelength increases with the temperature increasing linearly. The larger the refractive index and the thermo-optic coefficient of the encapsulating liquids are, the more nonlinearity the spectral wavelength shifting with temperature changing is. When the MNFBG is surrounded with the liquid with the refractive index of 1. 456 and the thermo-optic coefficient of 4 ×10^-4 ℃ 1, the temperature sensitivity of the reflection wavelength can reach up to -50.3 pm/℃. These spectral characteristics of MNFBG are connected with the surround liquid, the temperature and the size of FBG. Through effectively controlling these correlative factors, more functional applications of FBG will be realized in different fields.