Study On Silicon-based Raman Laser Application In The Measurement Of Gases Concentration

The poisonous, harmful ,combustible and explosive gases produced in the process of mine mining, mechanical manufacturing and melting , affected the human health and survival environment seriously. So it is the basic guarantee of the human safety and healthy lives to monitor these gases effectively in time. Fiber loop ring-down spectral technology is based on the fiber communication and fiber sensor technology, because of the high sensitivity, and is widely used to measure the trace gases. Due to the high power density needed for the pump source to measure the trace gases, with the trend to pursue the high performance price ratio, I make a research on the Si-based Raman laser, and apply it to measure the gas concentration. The major content includes:Firstly, the gas concentration measurement principle of fiber loop cavity ring-down spectroscopy is analyzed, and the corresponding mathematical model is established. At the same time, the factor that influences the concentration precision is discussed. The stimulated Raman scattering which is the principle of Raman laser is introduced, and is investigated theoretically.Secondly, the gas concentration measurement system based on fiber loop cavity ring-down spectral technology is introduced and the Si-based Raman laser system is mainly investigated. Then the performance and principle of the key cells of the system are analyzed, and the carrier lifetime that affects the output performance of Raman laser is analyzed theoretically. At last, the lifting wavelet transform is adopted to denoise the experimental data, and the performance of the lifting wavelet transform to denoise is simulated.Finally, the performance of the Si-based Raman laser is analyzed experimentally. The system chooses the methane as the detected gas, and is demonstrated experimentally. The lifting wavelet transform to improve the measurement precision is demonstrated by the compared experiment. The absorption performance of methane and the relationship between the ring-down time and gas concentration are analyzed.