基于模间干涉的反射型全光纤液体折射率传感器

Reflection-type All-fiber Liquid Refractive Index Sensor Based on Inter-mode Interference

基于模间干涉原理设计并实验制作了一种反射型全光纤液体折射率传感器,该传感器是由一段无芯光纤熔接在两个单模光纤之间制作而成。其工作原理是由单模光纤和无芯光纤耦合点处激发出高阶模式,经过末端单模光纤端面的反射,在无芯光纤和单模光纤界面发生二次耦合,从而形成模间干涉。数据处理后可得,在氯化钠、甘油和蔗糖溶液中传感器有不同的折射率灵敏度,每种溶液分别为-104.14345dB/RIU、-153.91078dB/RIU和-95.40521dB/RIU。温度灵敏度为35.27pm/℃,温度在强度上的改变对折射率的测量影响非常小,相对于该波峰波长漂移量可以忽略不计,温度的串扰较小。所提出的传感器具有结构简单、机械性能优良和灵敏度高等优点,在液体折射率的监测领域具有一定的应用潜力。

A reflective all-fiber liquid refractive index sensor is designed and experimentally fabricated based on the principle of intermodal interference,which is made by fusing a section of coreless fiber between two sin-gle-mode fibers.The working principle is that the higher-order modes are excited at the coupling point of the sin-gle-mode fiber and the coreless fiber,and after reflection from the end face of the single-mode fiber,the secondary coupling occurs at the interface of the coreless fiber and the single-mode fiber,which results in the formation of in-termodal interference.Data processing yields different refractive index sensitivities for the sensor in sodium chlo-ride,glycerol,and sucrose solutions,-104.14345 dB/RIU,-153.91078 dB/RIU,and-95.40521 dB/RIU for each solution,respectively.The temperature sensitivity is 35.27 pm/°C,and the change in temperature at the intensity has a very small effect on the refractive index measurements.The wavelength drift with respect to this peak is negli-gible and the crosstalk of temperature is small.The proposed sensor has the advantages of simple structure,excel-lent mechanical properties and high sensitivity,and has certain potential applications in the field of liquid refractive index monitoring.