This letter presents the development and characterization of a Fabry-Perot interferometer (FPI) for the detection of dissolved ammonia. The FPI cavity is obtained by the alignment of two single mode fibers (SMFs), where a mixture of ultraviolet (UV) curable resin and Oxazine 170 perchlorate is positioned in the gap between both SMFs. The sensor operation principle is based on the chemical reaction between the dissolved ammonia and the Oxazine 170 perchlorate. Such reaction leads to the refractive index variation in the FPI cavity, which results in a wavelength shift of the reflected spectrum. The water absorption and temperature effects in the sensor response are characterized. Such characterizations demonstrate that a good sensor performance is achieved when it is submerged in aqueous solutions for about one hour (to enable the water absorption) and at controlled temperature conditions. Then, the FPI sensor is submerged in ammonia solutions with concentrations ranging from 0 to 700 ppb (in 100 ppb steps). Results show a reversibility of the proposed sensor and a high sensitivity of 4.3 pm/ppb (4.3 nm/ppm). Thus, the proposed sensor can be used on the detection of low concentrations of ammonia (in a sub-ppm range) with one of the highest reported sensitivities of ammonia sensors, which makes it suitable for water quality monitoring.This letter presents the development and characterization of a Fabry-Perot interferometer (FPI) for the detection of dissolved ammonia. The FPI cavity is obtained by the alignment of two single mode fibers (SMFs), where a mixture of ultraviolet (UV) curable resin and Oxazine 170 perchlorate is positioned in the gap between both SMFs. The sensor operation principle is based on the chemical reaction between the dissolved ammonia and the Oxazine 170 perchlorate. Such reaction leads to the refractive index variation in the FPI cavity, which results in a wavelength shift of the reflected spectrum. The water absorption and temperature effects in the sensor response are characterized. Such characterizations demonstrate that a good sensor performance is achieved when it is submerged in aqueous solutions for about one hour (to enable the water absorption) and at controlled temperature conditions. Then, the FPI sensor is submerged in ammonia solutions with concentrations ranging from 0 to 700 ppb (in 100 ppb steps). Results show a reversibility of the proposed sensor and a high sensitivity of 4.3 pm/ppb (4.3 nm/ppm). Thus, the proposed sensor can be used on the detection of low concentrations of ammonia (in a sub-ppm range) with one of the highest reported sensitivities of ammonia sensors, which makes it suitable for water quality monitoring.

中文翻译：

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使用法布里-珀罗干涉仪对水中的氨进行高灵敏度检测


这封信介绍了用于检测溶解氨的法布里-珀罗干涉仪 (FPI) 的开发和表征。 FPI 腔是通过对准两个单模光纤 (SMF) 获得的，其中紫外线 (UV) 固化树脂和 Oxazine 170 高氯酸盐的混合物位于两个 SMF 之间的间隙中。传感器的工作原理基于溶解的氨和恶嗪 170 高氯酸盐之间的化学反应。这种反应会导致 FPI 腔内的折射率发生变化，从而导致反射光谱的波长偏移。表征了传感器响应中的吸水率和温度效应。这些特征表明，当在受控温度条件下将其浸入水溶液中约一小时（以实现吸水）时，可以获得良好的传感器性能。然后，将 FPI 传感器浸入浓度范围为 0 至 700 ppb（以 100 ppb 为步长）的氨溶液中。结果显示所提出的传感器具有可逆性和 4.3 pm/ppb (4.3 nm/ppm) 的高灵敏度。因此，所提出的传感器可用于检测低浓度的氨（在亚 ppm 范围内），具有报道的氨传感器最高灵敏度之一，这使其适合水质监测。这封信介绍了该传感器的开发和应用用于检测溶解氨的法布里-珀罗干涉仪 (FPI) 的表征。 FPI 腔是通过对准两个单模光纤 (SMF) 获得的，其中紫外线 (UV) 固化树脂和 Oxazine 170 高氯酸盐的混合物位于两个 SMF 之间的间隙中。 传感器的工作原理基于溶解的氨和恶嗪 170 高氯酸盐之间的化学反应。这种反应会导致 FPI 腔内的折射率发生变化，从而导致反射光谱的波长偏移。表征了传感器响应中的吸水率和温度效应。这些特征表明，当在受控温度条件下将其浸入水溶液中约一小时（以实现吸水）时，可以获得良好的传感器性能。然后，将 FPI 传感器浸入浓度范围为 0 至 700 ppb（以 100 ppb 为步长）的氨溶液中。结果显示所提出的传感器具有可逆性和 4.3 pm/ppb (4.3 nm/ppm) 的高灵敏度。因此，所提出的传感器可用于检测低浓度的氨（在亚 ppm 范围内），具有报道的最高灵敏度的氨传感器之一，这使其适合水质监测。