| Laser-diode-pumped solid-state lasers (DPSL) are named all-solid-state lasers. Due to their advantageous properties such as high efficiency, high stability, compactness, and etc., those lasers have been widely used for many applications in military, medicine and scientific fields. This dissertation is concerned on laser diode (LD) end-pumped continuous wave (cw) and Q-switched Nd:YVO4 laser with Cr4+:YAG as the intracavity saturable absorber.The main contents are as follows:1. A brief introduction to DPSL. The development and the characteristics of DPSL were summarized. And the characteristics of Nd and Cr ions laser materials were described in detail; especially, some key parameters of several commonly used Nd ion crystals were also listed.2. The laser property comparison of off-axially-cut and a-cut Nd:YVO4 lasers in the cw operation domain. We experimentally found the off-axially-cut crystal shared some properties of the a-cut one. Our experiments demonstrated that both 45?off-axially-cut and a-cut crystals could be operated with the low pumping thresholds (20 mW) for the cw lasers. The slope efficiency of the a-cut Nd:YVO4 laser was about 42%, while that of the off-axially-cut Nd:YVO4 laser was about 35%. Furthermore, the light emitted from the off-axially-cut laser was linearly polarized.3. The laser property comparison of off-axially-cut and a-cut Nd:YVO4 lasers in the passive Q-switched domain. As compared to a-cut Nd:YVO4 lasers, our experiments confirmed that 45-off-axially-cut Nd:YVO4 exhibited better performance for passive Q-switching over a-cut ones, which consequently enabled laser outputs of higher peak powers and narrower pulse widths. For the passively Q-switched laser, slope efficiencies of the a-cut and off-axially-cut lasers were 11.3% and 8.5%, respectively. For the 45-off-axially-cut crystal, we obtained a peak power of 1.5 kWwith a 3.9-ns pulse width and 11.1-kHz repetition rate under the LD pump power of 1340 mW. We also found that the 45-off-axially-cut Nd:YVO4 passively Q-switched laser was easy to operate in the single longitudinal mode.4. Summary to the previous work. By analyzing the experimental results, we believe that the 45-off-axially-cut Nd:YVO4 exhibited parts of properties both the a-cut and c-cut crystals because of the competition between polarization and polarization simulated emissions. As far as we know, the 45-off-axially-cut and a-cut Nd:YVO4 were compared thoroughly first time in this dissertation. It was confirmed the 45-off-axially-cut Nd:YVO4 was a kind of crystal between a-cut and c-cut one for passively Q-switched laser; furthermore, it implied we could control laser parameters by varying the cutting direction of the laser crystal.The thesis is organized as follows. In chapter 1, we introduce the background on DPSL and some crystals doped with Nd or Cr ions. Chapter 2 describes the a-cut and off-axially-cut Nd:YVO4 cw lasers. Chapter 3 mainly presents the characteristic difference between a-cut and off-axially-cut Nd:YVO4 lasers in passive Q-switched operation. A brief summary of the whole work is given in chapter 4. |
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