Metal Sulfide Based All-fiber-optic Humidity Sensor

Humidity is an important parameter in many fields such as agriculture, industry. However electronic humidity sensors are unsuitable for remote detection or for using in environments with strong electromagnetic-interference. Compared to the traditional electronic sensors, fiber optic sensors are compact, lightweight, and also resistant to corrosive, heat, electromagnetic. In this thesis, we have focused on investigating fiber optic humidity sensors, which are potential to overcome the drawbacks of electrical sensors as mentioned above. The main contents are as following.(1) We demonstrate a novel all-fiber-optic humidity sensor comprised of a WS2 film overlay on a side polished fiber(SPF). This sensor can achieve optical power variation of up to 6 d B in a relative humidity(RH) range of 35%RH-85%RH. Furthermore, it has a linear correlation coefficient of 99.39%, sensitivity of 0.1213 d B/%RH, and a humidity resolution of 0.475%RH.(2) We fabricate a novel all-fiber-optic humidity sensor comprised of a WS2 film overlay on a micro-nano fiber(MNF). This sensor can achieve optical power variation of up to 9.183 d B in a relative humidity(RH) range of 35%RH-90%RH. Furthermore, it has a linear correlation coefficient of 98.89%, sensitivity of 0.1964 d B/%RH, and a humidity resolution of 0.255 %RH.(3) We make a humidity sensor comprised of a Cu S film overlay on a side polished fiber and discover that Cu S is a humidity sensing material.The innovation work of this paper is that we demonstrate the novel all-fiber-optic humidity sensor comprised of a WS2 film overlay on a side polished fiber and micro-nanofiber.