This Small Business Innovative Research Phase II proposal seeks to develop a low cost, robust, highly precise and accurate CO2 monitoring system. This system will employ a novel mid-infrared laser source, which was successfully demonstrated during Phase I along with a bench-scale laboratory sensor. Quantitative analysis of the Phase I results showed that the goal of determining the mole fraction of CO2 in atmospherically relevant gas mixtures with a precision of 0.05% min-1 was achieved. The Phase II project will significantly refine approach and improve the long term stability such that an onboard gas calibration system needs to operate at most once-per-hour. The resulting compact, fully integrated Phase II prototype will enable completely automated CO2 concentration measurements to be routinely performed with unprecedented accuracy. Commercial systems based on the Phase II prototype will be refined and marketed during Phase III. Additionally, the core technology can be applied for the detection of other target species such as CO2 isotopes, methane, and CO.