Real-Time N(2)O Gas Detection System for Agricultural Production Using a 4.6-μm-Band Laser Source Based on a Periodically Poled LiNbO(3) Ridge Waveguide

This article describes a gas monitoring system for detecting nitrous oxide (N(2)O) gas using a compact mid-infrared laser source based on difference-frequency generation in a quasi-phase-matched LiNbO(3) waveguide. We obtained a stable output power of 0.62 mW from a 4.6-μm-band continuous-wave laser source operating at room temperature. This laser source enabled us to detect atmospheric N(2)O gas at a concentration as low as 35 parts per billion. Using this laser source, we constructed a new real-time in-situ monitoring system for detecting N(2)O gas emitted from potted plants. A few weeks of monitoring with the developed detection system revealed a strong relationship between nitrogen fertilization and N(2)O emission. This system is promising for the in-situ long-term monitoring of N(2)O in agricultural production, and it is also applicable to the detection of other greenhouse gases.