Research Of LD-pumped All-solid-state V:YAG Passively Q-switched Laser Characteristics

Recently, laser-diode (LD) pumped solid-state laser has become a popular and important research area. Compared to other lasers, this kind of laser has wide applications in the fields such as laser telecommunication, information processing, military, medical and industry, due to the advantages such as all solid state, simplicity, long lifetime, high stability and high pump efficiency.The main research content of this dissertation is LD-pumped all-solid-state V:YAG passively Q-switched laser characteristic. By using the fiber-coupled laser-diode as the pump source, Nd:GdVO4 and Nd:GdxY1-xVO4 crystals as the gain media, we have studied the performance of the output pulse in the passively Q-switched laser with V:YAG saturable absorber, and the performance of the frequency-doubled output pulse when we add the KTP crystal to the laser cavity. Meanwhile, the unwonted variation of pulse repetition rate caused by the thermal lens effect in the Nd:GdVO4/V:YAG laser is theoretically explained, and the coupling wave rate equations are given to theoretically analyze the properties of the frequency-doubled Nd:GdVO4 laser.The main contents of this dissertation include:1. We have presented the performance of an LD-pumped Nd:GdVO4 laser passively Q-switched with V:YAG saturable absorber of initial transmission as high as 96% at 1342 nm. The laser characteristic parameters including average output power, pulse width, pulse repetition rate, single-pulse energy and peak power have been measured for different transmissions of the output couplers and different pump powers. Besides, the unwonted variation of pulse repetition rate with pump power found in the experiment is theoretically explained.2. Adopting the folded cavity structure with three mirrors, we have presented the performance of an LD-pumped passively Q-switched intracavity-frequency-doubled Nd:GdVO4/KTP red laser with V:YAG saturable absorber at 671 nm. The average output power, pulse width, pulse repetition rate, single-pulse energy and peak power under different small-signal transmissions of V:YAG and different pump powers have been measured. Besides, taking the transversal and longitudinal distributions of the intracavity photon density, the transversal distributions of the pump beam, the population-inversion density and the saturable absorber ground-state population density into account, and then considering the harmonic conversion as a nonlinear loss of the fundamental wave, we use the rate-equation theory to analyze the properties of the frequency-doubled Nd:GdVO4 laser.3. Using Nd:GdxY1-xVO4 mixed crystal as gain medium, we have presented the performance of an LD-pumped Nd:GdxY1-xVO4 laser passively Q-switched with V:YAG saturable absorber at 1342 nm, and the performance of an LD-pumped passively Q-switched intracavity-frequency-doubled Nd:GdxY1-xVO4/KTP red laser with V:YAG saturable absorber at 671 nm. The proportion of element Gd to element Y is different in Nd:GdxY1-xVO4 mixed crystal. Four different situations of the fundamental pulse and two different situations of the frequency-doubled pulse are experimentally measured and compared, respectively.The main innovations of this dissertation are as follows:1. We firstly present the performance of an LD-pumped Nd:GdVO4 laser at 1342nm passively Q-switched with V:YAG saturable absorber of initial transmission as high as 96%. Meanwhile, the unwonted variation of pulse repetition rate with pump power found in the experiment is theoretically explained.2. We firstly present the theoretical and experimental study of an LD-pumped passively Q-switched intracavity-frequency-doubled Nd:GdVO4/KTP red laser with V:YAG saturable absorber in aâ…¤-type resonator. The numerical solutions of the rate equations are consistent with the experimental results.3. We firstly present the performance of an LD-pumped passively Q-switched intracavity-frequency-doubled Nd:GdxY1-xVO4KTP (x=0.19 and 0.83) red laser with V:YAG saturable absorber at 671 nm. The laser properties for different proportions of element Gd to element Y are experimentally measured and compared, respectively.