Agarose coated macro-bend fiber sensor for relative humidity and temperature measurement at 2?μm

摘要： We proposed an agarose coated macro-bend fiber (AC-MBF) sensor for relative humidity and temperature measurement at 2 μm. Stronger resonance dips in the bent fiber sensor can be found at 2 μm region, which is at the peak of water absorption better for humidity sensing. Experimentally, such an AC-MBF sensor was very sensitive to humidity at 2 μm region. The highest sensitivity of 0.314 nm/%RH was achieved in the range of 40–95%, which was much higher than the wavelength–modulated sensors at 1.5 μm reported previously. Meanwhile, the sensor is also very sensitive to temperature. The maximum temperature sensitivity of the macro-bend fiber sensor is 5.37 nm/°C. Additionally, AC-MBF sensor is with fast response time and recovery time of ～300 ms and 600 ms, respectively.