Research On Electro-optical Frequency Modulation Technology For LD-pumped Single-mode1.06μm Solid-state Laser

In recent years, on the need of high-precision and long-distance of measurement,coherent laser ranging system has got a great deal of attention, but of which the mostimportant thing is to obtain the broad-band linear frequency modulation laser (LFM).Meanwhile, the LFM laser has also been widely used in optoelectronics, spectroscopy,bio-medical and other aspects. Thus, there is a great significance for the study of LFM.Stable single frequency laser with excellent monochromatic, long coherence length,narrow line-width, high beam quality, low noise and stabilized output frequencycharacteristics, has played an extremely important role in optical precision measurement,laser communication and coherent laser ranging system. Therefore, the first condition forlinear frequency modulation of the output laser is to have stable single frequencyoperation.Theoretically, the principles of the transverse mode, longitudinal mode and thecorresponding mode selecting methods are mainly focused on. By comparing thecharacteristics of mode selection methods, the schematic of the F-P etalon method isselected, and the corresponding numerical simulation analysis is performed. The spatialhole burning effect which has impacts on the output single longitudinal mode and thesolutions for it are described in detail. These would establish theoretical basis for thesubsequent experimental research. For the problem of the stability of the output laser, theinfluential factors are also analyzed in theory and appropriate solutions are developed.Finally, combining with the LFM principle, electro-optical frequency modulation projectis formulated, following with the corresponding theoretical analysis.Based on the theory of the foregoing analysis, we design the LD pumped singlefrequency Nd:YVO4laser. Furthermore, a series of specific experimental analyses aboutthe output single longitudinal mode laser from the spectrum, output power andpolarization aspects are finished, of which the maximum output power is212.49mW andthe polarization state is linearly polarized. The results show that the selection ofappropriate F-P etalons and output mirrors is particularly important for the certain lengthof single-frequency laser cavity. Then, according to the established frequency modulationscheme, the experimental studies on RTP crystal for the angle and the electro-opticalfrequency modulation are conducted. The experimental analyses shows that themaximum range of the angle frequency modulation is0.65GHz. The electro-opticaltuning rang in the horizontal direction of0.54GHz and vertical direction tuning range of1.17GHz are all affected by F-P etalons. Eventually, aiming at the impact of the F-Petalon for LFM, the corresponding experimental studies are carried out with themaximum frequency range up to2.08GHz.