We propose to develop a compact, robust, optically-based sensor for local and remote sensing of oxygen (O2) at 1.26 µm, carbon dioxide (CO2) at 1.56 µm and other species in spectral region of up to 2ìm with accuracy of the order of 0.5 1 ppm, allowing a very high out-of-band rejection of spurious solar background radiation. This sensor will utilize a widely tunable narrowband optical filter in conjunction with a wideband optical source (sun light or a commercially available broadband source) in combination with built-in calibration laser diode to make absorption measurements as well as evaluate atmospheric parameters such as pressure, temperature and density. Proposed instrumentation can be valuable for NASAs ASCENDS program with broad scope applications in the measurement of atmospheric parameters and multi-species concentration measurement including CO2. Instrumentation will be environmentally rugged and compact and will possess auto-calibration capabilities, fast response time (microseconds to milliseconds range) and low-power consumption. Phase I work will involve building and characterizing a complete laboratory scale system so that a final system can be constructed in Phase II. TRL range at onset of Phase I is 2 at end 3-4; Phase 2 at onset 4 at end 5-6.