通过化学腐蚀方法制作了一种基于光纤气泡级联马赫曾德干涉液体折射率传感器.在细芯光纤两端熔接切割端面被腐蚀的单模光纤,构成气泡-细芯光纤-气泡结构,该结构中两个气泡耦合光场,细芯光纤作为传感臂,构成光纤马赫曾德干涉仪.对该传感器的干涉谱能量随折射率的变化规律进行了研究,结果表明：干涉谱的能量与环境折射率之间存在较好的线性关系,同时波长变化对环境折射率变化不敏感; 当外界折射率变化范围在1.345~1.389时,传感器的灵敏度为－216.21dB/RIU.该传感器在生物化学领域有较好的应用前景.

A kind of optical fiber refractive index sensor based on a fiber core etched air-bubble in-fiber Mach-Zehnder interferometer was proposed and demonstrated. A core etched standard single mode fiber was spliced to a thinner core single mode fiber to form an air bubble at the connecting point. By this method, a section of thinner core fiber was cascaded between two air bubbles to form a structure of (Air-Bubble)-Thin core fiber-(Air-Bubble) in-fiber Mach-Zehnder interferometer as a refractive index sensor. The air-bubble in the sensor serves as an optical coupler for modes conversion and the thin core fiber serves as sensing beams. The transmission spectrum of sensor was studied by experiment. The results show that, the dip power of the interference fringes changes with respect to surrounding refractive index with a good linearity,at the same time,the dip wavelength keeps low dependence on RI. The sensitivity of the sensor is －216.21dB/RIU in the range of 1.345~1.389. The sensor is a good potential candidate for bio-chemical measurements.