A CNT-coated refractive index sensor based on Michelson interferometer with thin-core fiber

摘要

A refractive index sensor, which is based on Michelson interferometer (MI) with a thin core fiber (TCF) coated by CNT (Carbon Nanotube), is proposed and experimentally demonstrated. This sensor is fabricated by the splice of a sectioned single mode fiber (SMF) on one end of TCF, and the other end is turned into a circular arc by fusion discharge. Such an all-fiber MI incorporates an intermodal interference between the core mode and the cladding modes. CNT is coated on the surface of the TCF. With the variations inside the environmental refractive index (RI), the shift of the wavelength and intensity of the interference pattern have been brought about. Experimentally, sensitivity of 178.88 dB/RIU (refractive index unit), 165.77 nm/RIU, as well as a resolution of 5.59 x 10(-4) RIU and 1.21 x 10(-4) RIU, are achieved respectively within a field ranging from 1.334 to 1.371 RIU. Moreover, CNT is better than silicon materials in compatibility, and it will not be washed away after its being adsorbed to the surface of optical fibers. In addition, its application could be better implemented in actual measurements, due to its insensitivity to temperature.