The sensing setup for detection and measurement of carbon dioxide and methane was designed. Absorption spectra of many compounds indicate several weak peaks around 1400-1600 nm wavelength. Thus, tunable lasers with 20 micron core photonic bandgap fiber matching above wavelengths were chosen for the optical measurement system. Measurements were performed at low pressure to eliminate pressure broadening effect and to sharpen the absorption peaks. The angled cut was performed to improve signal to noise ratio.