| Nonlinear frequency conversion technology has established itself as a reliable and efficient way to obtain diverse and versatile laser sources with novel and valuable wavelengths. It has been one important aspect and one of the focus topics in optics. In the past several decades, all kinds of nonlinear optical effects have been researched deeply and widely. For example, the second order nonlinear optical effects such as second harmonic generation, sum frequency generation, differential frequency generation, and optical parametric oscillation, etc, and the third order nonlinear optical effects such as four wave mixing, stimulated Raman scattering, and stimulated Brillouin scattering, etc. In all kinds of nonlinear optical effects, we focus on optical parametric oscillation and stimulated Raman scattering. Both of them all efficient nonlinear optical processes and from them high output power can be generated. For optical parametric oscillation, we mainly study the output time characteristics of intracavity singly resonated optical parametric oscillators. As for stimulated Raman scattering, we put our efforts on the realization of sodium lasers through crystalline Raman laser technology. Sodium lasers have important applications in astronomy and national defense, and it is import research field in nonlinear optics nowadays.In this dissertation, we experimentally studied the passively Q-switched intracavity Nd:Y3Al5O12(Nd:YAG)/KTiOAsO4(KTA) optical parametric oscillator (OPO), and through theoretical simulations and analyses based on rate-equation model, we made reasonable explanations to the experimental results. In order to realize589nm sodium laser generations, we designed two regimes of frequency doubled crystalline Raman lasers. One is frequency doubled c-cut Nd:YV04Raman laser, the other is frequency doubled Nd:Gd3Ga5O12(Nd:GGG)/BaW04Raman laser. We performed detailed studied about their operating characteristics. The main contents of this dissertation are as follows:1. Nd:YAG/Cr4+:YAG/KTA optical parametric oscillator was designed and realized to simultaneously obtain parametric waves at1.5μm and3.5μm. Using fiber-coupled diode laser (808nm) as the pumping source, Nd:YAG as the laser material, Cr4+:YAG as the passive Q-switch, and KTA as the nonlinear crystal, we realized intracavity singly resonated optical parametric oscillator. With a pumping power of11.4W, we obtained1.05W of total parametric wave power, in which772mW was for the signal wave (1535nm) and278mW for the idler wave (3467nm). The pulse repetition rate was36.5kHz. The pulse widths were6.7ns and2.9ns for the signal and idler waves, respectively. So the signal pulse width was longer than the idler one. Hence we experimentally proved that signal pulse width is longer than the idler one in singly resonated OPO.2. We made theoretical simulations and analyses on the experiments above. Novel theoretical model based on rate equations was set up in order to simultaneously deal with the output characteristics of both the signal and idler waves in intracavity singly resonated OPO. Then this model was adopted to the passively Q-switched intracavity singly resonated Nd:YAG/Cr4+:YAG/KTA OPO. The output characteristics of both the signal and idler waves were obtained theoretically. The theoretical results were consistent with the experimental ones. They also showed that the signal pulse width was longer than the idler one in singly resonated OPO.3. Diode pumped Nd:GGG/BaW04crystalline Raman laser was realized. Using fiber-coupled diode laser (808nm) as the pumping source, Nd:GGG as the laser material, and BaWO4as the Raman material, we realized acousto-optically Q-switched intracavity Raman lasers. With a pumping power of8.84W and a pulse repetition rate of10kHz, we obtained1.4W of1178nm Raman laser power. The corresponding optical-to-optical (diode-to-Raman laser) conversion efficiency was15.8%.4. Based on the Raman laser above, by choosing KTiOPO4(KTP) as the frequency doubling crystal, we realized diode pumped Nd:GGG/BaWO4/KTP yellow laser. And589nm sodium laser was generated. Intracavity frequency doubling technique was employed here. With a pump power of8.84W and a pulse repetition rate of10kHz, we obtained0.82W of589nm laser. The corresponding optical-to-optical (diode-to-yellow laser) conversion efficiency was9.3%. The pulse width was9ns and the peak power was9.1kW.5. Using fiber coupled diode laser (880nm) as the pumping source, we studied the acousto-optically Q-switched c-cut Nd:YVO4(c-Nd:YVO4) self-Raman laser. With an absorbed diode power of15.8W and a pulse repetition rate of45kHz, we obtained2.14W of1178nm Raman laser. The corresponding optical-to-optical (diode-to-Raman laser) conversion efficiency was13.5%.6. Also using KTP as the frequency doubling crystal, we obtained589nm sodium laser by frequency doubling of the c-Nd:YVO4self-Raman laser. With a pump power of12.4W and a pulse repetition rate of40kHz, we obtained1.24W of589nm laser. The corresponding optical-to-optical (diode-to-yellow laser) conversion efficiency was10%. And the beam quality factors (M2) were2.78and3.01in horizontal and vertical directions, respectively.7. Using fiber coupled diode laser (880nm) as the pumping source, we realized the acousto-optically Q-switched c-Nd:YVO4/a-YVO4Raman laser. With an absorbed diode power of18.1W and a pulse repetition rate of45kHz, we obtained2.34W of1178nm Raman laser. The corresponding optical-to-optical (diode-to-Raman laser) conversion efficiency was12.9%.8. Considering output power, tuning characteristics of central wavelength and beam quality, we made comparisons between the c-Nd:YVO4/a-YVO4Raman laser and c-Nd:YV04self-Raman laser. Through controlling the temperature of a-YV04crystal, we studied the temperature tuning characteristics of the c-Nd:YVO/a-YVO4Raman laser. All the results showed that compared to c-Nd:YVO4self-Raman laser, c-Nd:YVO4/a-YVO4Raman laser had advantages in output power, wavelength tunability and beam quality.The main innovations of this dissertation are as follows:1. For the first time, parametric waves at1.5μm and3.5μm were obtained simultaneously from Nd:YAG/Cr4+:YAG/KTA optical parametric oscillator. We obtained a total output power of1.05W, in which772mW was signal wave (1535nm) and278mW was idler wave (3467nm).2. For the first time, we experimentally proved that signal pulse width is longer than the idler one in singly resonated OPO. In the experiments mentioned above, the pulse widths were6.7ns and2.9ns for the signal and idler waves, respectively. So the signal pulse width was longer than the idler one.3. Novel theoretical model was set up based on rate equations in order to simultaneously deal with the output characteristics of both the signal and idler waves in intracavity singly resonated OPO. For the first time, we theoretically proved that signal pulse width is longer than the idler one in singly resonated OPO.4. For the first time, we realized diode pumped Nd:GGG/BaWO4Raman laser. The highest power of1.4W was obtained, corresponding to an optical-to-optical (diode-to-Raman laser) conversion efficiency of15.8%.5. For the first time, we realized diode pumped frequency doubled Nd:GGG/BaWO4Raman laser. The highest sodium laser power of0.82W was obtained, corresponding to an optical-to-optical (diode-to-yellow laser) conversion efficiency of9.3%.6. For the first time, we realized diode pumped c-Nd:YVO4/a-YVO4Raman laser. The highest power of2.34W was obtained, corresponding to an optical-to-optical (diode-to-Raman laser) conversion efficiency of12.9%.7. Considering output power, tuning characteristics of central wavelength and beam quality, we made comparisons between the c-Nd:YVO4/a-YVO4Raman laser and c-Nd:YVO4self-Raman laser. For the first time, we made the conclusion that compared to c-Nd:YVO4... |
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