报道了一种具有微结构缺陷的折射率传感器,并对其折射率特性进行了实验研究.将一部分薄芯光纤熔接于标准单模光纤中,由于插入的薄芯光纤和单模光纤纤芯失配,导致包层的高次模被激发并与纤芯模在单模光纤内形成干涉仪.通过减小薄芯光纤的包层直径,以增强包层中的传输模在环境中的倏逝场,从而提高对环境折射率测量的灵敏度.实验表明,该折射率传感器具有损耗低、成本低、灵敏度高和线性度好等特点.

A refractive-index sensor with micro-structured defect was proposed and demonstrated,and its refractive-index characteristics were studied experimentally.After inserting a segment of thin-core fiber into a standard single-mode fiber,high-order cladding modes were excited and interfered with the core mode to form an in-fiber modal interferometer because of the mismatch between thin-core fiber and standard single-mode fiber .By decreasing of the cladding-diameter of the thin-core fiber,the evanescent field of the cladding modes was enhanced,which improved the sensitivity of refractive-index.Experimental results show that the proposed device has advantages of low loss,low cost,high sensitivity and good linearity.