Pham Thanh Binh, Bui Huy, Le Huu Thang, Pham Van Hoi
Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Rd, Cau giay District, Hanoi 100000, Vietnam.
Small and Medium Enterprise Development and Support Center 1, Directorate for Standards, Metrology and Quality, 8 Hoang Quoc Viet Rd, Cau giay District, Hanoi 100000, Vietnam.
Sensors (Basel). 2016 Dec 22;17(1):7. doi: 10.3390/s17010007.
The necessity of environmental protection has stimulated the development of many kinds of methods allowing the determination of different pollutants in the natural environment, including methods for determining nitrate in source water. In this paper, the characteristics of an etched fiber Bragg grating (e-FBG) sensing probe-which integrated in fiber laser structure-are studied by numerical simulation and experiment. The proposed sensor is demonstrated for determination of the low nitrate concentration in a water environment. Experimental results show that this sensor could determine nitrate in water samples at a low concentration range of 0-80 ppm with good repeatability, rapid response, and average sensitivity of 3.5 × 10 nm/ppm with the detection limit of 3 ppm. The e-FBG sensing probe integrated in fiber laser demonstrates many advantages, such as a high resolution for wavelength shift identification, high optical signal-to-noise ratio (OSNR of 40 dB), narrow bandwidth of 0.02 nm that enhanced accuracy and precision of wavelength peak measurement, and capability for optical remote sensing. The obtained results suggested that the proposed e-FBG sensor has a large potential for the determination of low nitrate concentrations in water in outdoor field work.
环境保护的必要性推动了多种用于测定自然环境中不同污染物的方法的发展，包括测定源水中硝酸盐的方法。本文通过数值模拟和实验研究了集成在光纤激光器结构中的蚀刻光纤布拉格光栅（e-FBG）传感探头的特性。所提出的传感器被用于测定水环境中的低硝酸盐浓度。实验结果表明，该传感器能够在0-80 ppm的低浓度范围内测定水样中的硝酸盐，具有良好的重复性、快速响应，平均灵敏度为3.5×10 nm/ppm，检测限为3 ppm。集成在光纤激光器中的e-FBG传感探头具有许多优点，如波长偏移识别的高分辨率、高光学信噪比（OSNR为40 dB）、0.02 nm的窄带宽，这提高了波长峰值测量的准确性和精度，以及光学遥感能力。所得结果表明，所提出的e-FBG传感器在户外现场工作中测定水中低硝酸盐浓度方面具有很大潜力。
