Research On Coherent Spectroscopy Measurement Based On Semiconductor Laser Array

Spectral analysis technology has always been used as a measurement method and plays an indispensable role in biomedicine,molecular analysis,laser detection,optical fiber communication,etc.However,with the deepening of various fields,there is a higher demand for the accuracy,resolution and measurement range of spectral analysis.Among the spectral measurement and analysis methods,heterodyne interference spectroscopy can meet high-precision,high-resolution measurement requirements covering the entire C-band.In the measurement of heterodyne interferometry,the traditional mechanical frequency-modulated laser has many disadvantages,such as high price and large volume,when a semiconductor laser is used as a swept source,the sweep frequency range is relatively narrow,and spectral measurements covering the entire C-band range cannot be performed.In summary,this paper uses semiconductor laser array as the FM laser source to conduct heterodyne interference spectrum measurement.The main research contents of this paper are as follows:1.Based on the principle of heterodyne interference spectroscopy measurement and overall program analysis.Aiming at the method of high-performance heterodyne interference spectrum measurement,the principle analysis is carried out and verified by simulation.The overall scheme of heterodyne interference spectrum measurement is designed.2.Analysis of influencing factors based on heterodyne interference spectroscopy of semiconductor laser arrays.The performance of heterodyne interferometry is analyzed,and the factors affecting the performance of heterodyne interference spectrum measurement are simulated and analyzed,and the parameters are selected to improve the performance of heterodyne interference spectrum measurement.In addition,the analysis of the frequency sweep characteristics of semiconductor laser arrays,including the analysis of the influence of sweep frequency on heterodyne interference spectrum measurement and the splicing of the frequency range of semiconductor laser arrays.3.Research on calibration method of heterodyne interference spectrum measurement based on semiconductor laser array.The calibration module of heterodyne interference spectrum measurement of semiconductor laser array was designed,and the research of wavelength calibration method and power calibration method was carried out by scanning the single laser tube of different semiconductor laser array across different wavelength range.4.Analysis of experimental results based on heterodyne interference heterodyne interference spectroscopy of semiconductor lasers.The experimental verification of the swept frequency range splicing of the semiconductor laser array is carried out,and the continuous frequency sweep in the C-band range is realized,so that the heterodyne interference spectrum measurement of the semiconductor laser array can cover the entire C-band measurement.In the spectrum measurement experiment,the acquisition method is carried out with a large-bandwidth acquisition card,and the signal processing method on the host computer achieves a wavelength measurement accuracy of 0.372 pm.When using a hardware analog signal processing method for signal processing,a VCSEL vertical cavity laser array is used.The wavelength measurement accuracy of the swept source is 0.969 pm.When a single laser tube in the DFB laser array can sweep the laser array of two adjacent gas absorption peaks as a swept source,the wavelength measurement accuracy is 0.459 pm,which will be in the DFB laser array.When a single laser tube can only sweep the laser array of a single gas absorption peak as a swept source,the frequency range calibration of the interferometer is performed by the combination of the sweep frequency ranging method and the single-frequency laser interferometer.The wavelength measurement accuracy reaches 0.317 pm.After the system resolution is measured,the resolution of the system is determined.Reached 6MHz.In the power measurement experiment,when the DFB laser array is used as the swept source,the power measurement repeatability is within 0.2 mW,that is,within-6dBm.In this paper,based on the heterodyne interference spectroscopy system,the semiconductor laser array with lower cost,smaller volume and more convenient is used as the frequency-scanning laser source to achieve high-resolution,high-precision,spectral measurement methods covering the entire C-band.This type of laser source is used as a scheme for the heterodyne interference spectrum measurement of the swept laser source.The design and calibration method are studied to verify the feasibility of heterodyne interference spectrum measurement when the laser source is used as a swept laser source.