Nowadays, Global warming is a serious challenge to humanity and is also one of the acknowledged global environmental issues for the international community [1,2]. The most important reason for global warming is the exhausted greenhouse gas including CO2, N2O, CH4 and O3. Among of them, the gases of CO2 and CH4 exist both the largest emission and the biggest influence. Therefore, it is very import to detect and measure the two gases. CO2 and CH4 gas sensors based on the optical principle are very suitable to monitor a variety of explosive gases such as carbon dioxide [3-5]. This kind of sensor has the advantages of high accuracy, good selectivity, high reliability, independence on the oxygen, and long life etc. So, there are some optic fiber-based sensors developed for air pollution monitoring.