中文摘要：

提出了一种应用于海水盐度测量的单模异芯结构的光纤折射率传感器。在两段普通单模光纤（SMF28）之间熔接一段细芯单模光纤（TCSMF）,构成全光纤Mach-Zehnder干涉仪（MZI）。以0-40‰NaCl溶液作为测试溶液,测量宽带光源经MZI后的透射光谱,应用特征峰波长和光谱差分积分两种方法进行解调,特征峰波长漂移量和光谱差分积分值均与NaCl浓度呈较好的线性关系。采用光谱差分积分法对全波段透射光谱强度进行解调,累积因折射率不同引起的透射谱差异,理论上可获得的盐水浓度分辨率为9.17×10-4‰,较之波长解调法提高了近3个数量级。本文的折射率传感器具有结构简单、机械强度好、测量灵敏度高和对温度不敏感等优点,可应用于海水盐度测量。

英文摘要：

A novel refractometric sensor based on the single-mode hetero-core fiber structure for salinity measurements is proposed.A section of thin-core single-mode fiber（TCSMF） is spliced between two conventional SMF28 fibers to construct a Mach-Zehnder interferometer（MZI）.Measuring the transmission spectrum of broadband source through the MZI immersed in 0-40‰ NaCl solution,two demodulation schemes based on peak wavelength shift and integration of spectrum differentials are compared,and the results show that both the peak wavelength shift and the integration of spectrum differentials vary linearly with the NaCl concentration.The sensitivity of the latter is approximately 3 orders higher than that of the former since it integrates the spectrum differentials within the wavelength scan range,and its resolution can reach 9.17×10-4‰.The refractometric sensor is simple,robust,highly sensitive,and is insensitive to temperature,and suitable for salinity measurements.