Methane Sensor Based on High-Q Microsphere Whispering Gallery Mode

Abstract In this paper, the principle of the methane gas enhanced the laser absorption by the WGM of high-Q microsphere was studied. A taper optical fiber was used as a coupler to couple 1653.72 nm laser into a microsphere with a optical fiber handle to form whispering gallery mode(WGM). The resonant wavelength of the microsphere cavity was changed to 1653.72 nm by injecting heating light along the handle, so that one resonant wavelength of the microsphere is just 1653.72 nm. The 1653.72 nm laser forms WGM continuously to surround the microsphere, and the effective optical path is greatly increased, which increases the interaction distance with methane, and thus the sensitivity of methane detection is improved. The results show that the microsphere with WGM can be used as a gas sensor.