Spectroscopic detection of radiocarbon dioxide based on optical feedback linear cavity enhanced absorption spectroscopy

Abstract Spectroscopic detection of radiocarbon dioxide ( 14 CO 2 ) offers several advantages, including real‐time detection, on‐site measurement capability, and ease of operation. Here, we propose a novel 14 CO 2 detection technique that utilizes optical feedback linear cavity enhanced absorption spectroscopy. The feedback phase is actively compensated by adjusting the light path length. The combination of cavity‐based technique and optical feedback enables the recording of stable and enhanced 14 CO 2 spectra. Through Allan deviation analysis, a minimal detectable 14 CO 2 concentration of 3.5 parts‐per‐trillion is achieved. This technique has the potential to contribute to the monitoring of the radiocarbon emissions in the air of nuclear power plants.