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Silica Gel Coated Spherical Micro Resonator For Ultra-High Sensitivity Detection Of Ammonia Gas Concentration In Air, Arun Mallik, Gerald Farrell, Dejun Liu, Vishnu Kavungal, Qiang Wu, Yuliya Semenova
Silica Gel Coated Spherical Micro Resonator For Ultra-High Sensitivity Detection Of Ammonia Gas Concentration In Air, Arun Mallik, Gerald Farrell, Dejun Liu, Vishnu Kavungal, Qiang Wu, Yuliya Semenova
Articles
A silica gel coated microsphere resonator is proposed and experimentally demonstrated for measurements of ammonia (NH3) concentration in air with ultra-high sensitivity. The optical properties of the porous silica gel layer change when it is exposed to low (parts per million (ppm)) and even ultra-low (parts per billion (ppb)) concentrations of ammonia vapor, leading to a spectral shift of the WGM resonances in the transmission spectrum of the fiber taper. The experimentally demonstrated sensitivity of the proposed sensor to ammonia is estimated as 34.46 pm/ppm in the low ammonia concentrations range from 4 ppm to 30 ppm using an optical …