Study On The Output Characteristics Of Grating External-Cavity Semiconductor Lasers

Due to the excellent characteristics of narrow line-width, tunable, frequency stability etc. the external-cavity semiconductor lasers (ECSL) have been widely used in the fields of high-resolution spectrum analysis, optical fiber communication, measuring and testing biomedical medicine etc.In this thesis. the grating external-cavity semiconductor lasers are made as the research objects. First, the development and the applications of the external-cavity semiconductor lasers are introduced. Then, based on the comprehensive analysis of semiconductor lasers and blazed grating, and started from the rate equation of the external cavity under the condition of a strong feedback. the oscillations of the grating external-cavity semiconductor lasers are analyzed. At the same time. the characteristics of mode selection, power output, line-width reduction and wavelength tuning are studied. In addition, different factors which are influenced by the output power and line-width reduction of the Littrow external-cavity semiconductor lasers have been numerical simulated with Matlab software and Origin software. Moreover, based on the theoretical analysis and numerical simulation, the grating external-cavity semiconductor laser which has single longitudinal mode and highly-equality laser output is developed. When the continual output power reach 180mW at working current with 400mA, the threshold current will decline from 165mA to 118mA. Finally, the Output Characteristics of grating external-cavity semiconductor lasers are measured with all kinds of methods. At the same time, the line width measurement methods are emphasized in this thesis. When we use homodyne method, the spectral line-width of ECSL is 20 KHz. Therefore, Lasers which have working stability can be continuously exported.