摘要:
本文用琼脂糖水凝胶制作了插入损耗为−0.08 dB、在30%~100% RH相对湿度变化范围的光强变化为15 dB的双包层单模光纤湿度传感器，在25℃~34℃的不同温度条件下，检测了该传感器输出光强随相对湿度的变化。根据饱和水汽压与温度的关系和实验结果，证实了被测气体相对湿度较小时，琼脂糖涂层的吸湿能力强，对温度变化敏感；随着相对湿度的升高，吸湿能力降低。在25℃~34℃的温度变化范围内，被测气体相对湿度分别为30%、90%和100% RH时，传感器对温度的灵敏度分别为0.3 dB/℃、0.1 dB/℃和0 dB/℃。实验结果还证实，琼脂糖在饱和吸收水份后的折射率近似等于康宁光纤包层的。本文研究结果说明，在应用光纤湿度传感器时，必须同时监测被测气体的温度，才能严谨地确定被测气体的相对湿度。
A doubly cladding single-mode fiber humidity sensor with insertion loss of −0.08 dB and optical power variation of 9.47 dB/% RH in the humidity range from 30% to 100% RH was fabricated by agarose. Its responses to humidity range at the different temperature from 25˚C to 34˚C were tested with a climatic chamber. Based on the Goff-Gratch formula and the experimental results, it has been confirmed that the agarose coating have a great absorbent capacity in a low relative humidity. The sensor had the sensitivity of 0.3 dB/˚C, 0.1 dB/˚C and 0 dB/˚C at the relative humidity of 30% RH, 90% RH and 100% RH, respectively, in the temperature range from 25˚C to 34˚C. It has also been confirmed that the refractive index of agarose gel was almost equal that of Corningoptical fiber cladding material. It was concluded that the temperature of measured gas must be simultaneously monitored in the application of optical fiber humidity sensor and accurate determination of the RH of the gas.