Monitoring vibrations and CO₂ concentrations in gas pipelines and other critical infrastructure is crucial for detecting gas leaks and structural failures early. However, existing vibration sensors are unsuitable for harsh environments due to electromagnetic interference, limited frequency bandwidth detection, and material incompatibility. Traditional fiber optic vibration sensors using fiber Bragg gratings or interferometric techniques face challenges like complex fabrication, low sensitivity, and slow response times because they rely on detecting peak wavelength shifts. Further, simultaneously measuring both vibrations and CO₂ levels typically requires separate sensor systems with expensive laser sources and components, leading to increased complexity and cost. These limitations highlight the need for a simple, cost-effective and highly sensitive sensor system capable of real-time, concurrent monitoring of vibrations and CO₂ concentrations.

NETL’s invention introduces a low-cost, simplified system for simultaneous measurement of vibration and CO₂ concentration using a single tunable fiber ring laser. It features a highly sensitive ultrasonic vibration sensor enhancing the signal-to-noise ratio and resolution while operating over a wide frequency range (10 Hz to 400 kHz). For CO₂ sensing, a length of coreless optical fiber coated with TEOS serves as a gas sensor for CO₂. The laser output is tuned to the CO₂ absorption wavelength of ~1574.6 nm, which provides fast and accurate gas concentrations (10–100% CO₂), enabling real-time environmental sensing.