Abstract
In this thesis, we study the photoacoustic spectroscopy of CO2 molecule using a 1570 nm DFB diode laser. The output of a 6-mW DFB diode laser is sent into a photoacoustic cell which is filled with carbon dioxide. Because of the photoacoustic effect, the variation of absorption generates an acoustic wave. We use a microphone as a transducer to detect the photoacoustic signal. An additional photoacoustic system was used to remove the background noise. The sensitivity of the system is, which is comparable with other experiments. In order to improve the sensitivity of the photoacoustic system, a Fabry-Perot cavity was placed outside the photoacoustic cell to enhance the light intensity. Until now, we are not able to lock the Fabry-Perot cavity on the laser frequency very well due to some technical problems, e.g., the mechanical instability of the cavity. Further improvements are needed to detect the cavity-enhanced photoacoustic signal in the feature.