Temperature-Compensated Humidity Sensor Based on Hole-Assisted Three-Core Fiber

A temperature-compensated humidity sensor based on hole-assisted three-core fiber (HATCF) has been demonstrated. The three cores of HATCF act as two in-fiber directional couplers with a common communal direct-passing arm. The simultaneous measurement of temperature and humidity is achieved by integrating the refractive index matching solution and agarose film into the two in-fiber directional couplers respectively. The measured temperature and RH sensitivities are 3.399 nm/°C and 0.043 nm/%RH, respectively. Due to the capability of temperature compensation, the proposed sensor has the potential to be used for high precision humidity measurement.