A Fabry-Perot Fiber-Optic Interferometer for Highly Sensitive CO2 Detection Based on the Nanoparticles Self-Assembly Technology

The highly sensitive CO2 detective instrument is intensively studied recently for the atmosphere protection. Fiber-optic interferometer is widely used as a gas sensor because its interference wavelength can be influenced by the environmental refractive index. In this work, by adopting the nanoparticles self-assembly technology, a spherical optical device with a primary pore width of 8.13 nm and a specific surface area as large as 74.58 m(2)/g is fabricated. For gas detection, the larger the specific surface area of the device, the more gas molecules being adsorbed, resulting in a higher sensitivity. A Fabry-Perot fiber-optic interferometer is designed by mounting the self-assembled device on a fiber end face. In the experiment, it shows a fast response time of 21 s, a high wavelength sensitivity of 200 pm/%, and a wide detection range from 350 ppm to 36% for CO2 gas. It also performs a high selectivity, good repeatability, and immunity to the gas flow rate. Such a Fabry-Perot interferometer, as a standard lab-on-fiber device, will have a significant application potential for trace CO2 monitoring in the field of carbon capture, utilization, and storage (CCUS).