Research On All-solid-state High-performance The-master-oscillator-lasers

With the development of laser technology, All-solid-state high-performance the-master-oscillator-lasers have been widely used in the fields of airborne optical system, laser radar system and laser warning detection system etc., and have become the key laser source in application. For the conventional mirror-based lasers could not be operated under severe environmental conditions, polarization coupled electro-optically Q-switched Porro prism-based laser resonator design is employed for providing much higher misalignment tolerance, decreasing the power intensity, correcting thermally induced stress birefringence and achieving variable output reflectivity. To get hundred level of high power output laser with high beam quality, two-rod resonator with90°optical rotator has been intensively investigated due to its simple configuration for achieving a high power and high quality of100W-QCW-1064nm master oscillator. And the master oscillator power amplifier (MOPA) system was used for extracting higher output power. With the extensive demand of the high-tech industries and scientific research frontier, the ultraviolet, infrared all-solid-state lasers associated with the infrared and ultraviolet nonlinear optical crystals have become the foreland and hotspot in the field of high technology materials and laser. All-solid-state high-power Nd:YLF laser for laser wavelength and laser characteristics of its own has become a key fundamental frequency light source of visible light, UV/deep ultraviolet and infrared laser system. All-solid-state high-performance the-master-oscillator-lasers have become the research focuses owing to the value of important practical applications. This doctoral dissertation focuses on theoretical and experimental research of all-solid-state high-power1064nm E-Q Switch laser,100W/200W high-beam seed and Nd:YAG rod MOPA lasers and all-solid-state high-power Nd:YLF/LBO laser.The main contents of this dissertation are as follows:1. The characteristics of Nd:YAG laser crystal, structural design of pump, the pumping field distribution, crystal temperature distribution, thermal effect of crystal formation mechanism analysis, measurement and the elimination were deeply utilized for investigating thermal effects on laser gain medium. Effective thermal management of the laser gain medium was used for achieving high performance of all solid state laser system. 2. The parameters of E-Q switching laser in different cases were theoretically investigated. Initially the conventional plane-parallel resonator was experimentally investigated. For avoiding the damage spot and solving the beam aberration, polarization coupled electro-optically Q-switched Porro prism-based laser resonator was optimally designed for correcting thermally induced stress birefringence and providing much higher misalignment tolerance, etc. We have analyzed a Porro prism laser resonator with waveplates through Jones matrix formulation and derived generalized expressions in terms of azimuth angles and phase shifts introduced by these polarizing elements. The combination of Porro prism and waveplate in the gain and feedback arm determine the variable reflectivity of the resonator were also given. Especially the results for commercial Porro prisms have been added in to obtain the practical application. The specific case of zero dispersion Porro prism and abnormal waveplate Porro prism diode-pumped Nd:YAG laser have been experimentally investigated. And experimental results match well with the theoretical key parameters analysis for the Porro prism-based laser resonator.3. The characteristics of symmetrical convex-convex two-rod resonator with90°optical rotator were theoretically investigated. The results of detailed theoretical analysis carried out on the relationship between the beam quality, mode shapes and mode profile of temperature difference in the laser rod under different compensation conditions, which the distance between two rods was also counted in the relationship. To achieve the output laser with high beam quality and high power, the experiment design has been further optimized, where the resonator on the stability region and the beam size of TEM00mode in the rod were by theoretical analysis and numerical computation. And the Optical elements of misalignment sensitivity characteristics were also used for theoretical analysis and numerical computation in two-rod resonator with90°optical rotator. Then the research results provide theoretical basis for achieving high-performance of symmetrical convex-convex two-rod resonator with90°optical rotator and four-mirror ring cavity two-rod structure with90°optical rotator.4. Based on the characteristics of symmetrical convex-convex two-rod dynamic resonator with90°optical rotator,100W-QCW-1064nm high-beam quality(M2<1.5, peak power1250W) output non-polarized and polarized laser has been realized, where a specific L configuration was also utilized for investigating the characteristics dynamic resonator. And the (MOPA) technology was used for extracting200W-QCW-1064nm (M2<1.5, peak power2500W) high-beam quality output in the laser system, which the experimental and integrated researches were synchronized. Then the characteristics of dithering spot were employed for engineering applications that demand reliable operation. These results were experimentally verified as improving the performance of laser system.5. The characteristics of Nd:YLF crystal and Nd:YLF pumping head were studied. On the basis of the theory of frequency doubling, the characteristics of LBO crystal phase matching, the effective nonlinear coefficient and the critical and non-critical phase matching parameters were theoretically investigated and simulated. To provide theoretical guidance for the ring cavity structure design, the operation features of ring cavity were discussed in detail. With two c-axis orthogonal rod with90°optical rotator to compensate birefringence induced thermally, the circular beam could be realized. The mirrors and the end of rod were coated anti-reflection1μm wavelength. Based on the accomplished calculations and experiments, the symmetrical convex-convex two-rod dynamic resonator with90°optical rotator can be output the high-power and high-beam quality28W-QCW-1321nm laser. To our best knowledge, the power value obtained with the same resonator and rod Nd:YLF lasers are advanced in the world. On the basis of short cavity experiments, four-mirror ring cavity structure was designed for achieving the fundamental frequency18W-QCW-1321nm output laser. Then the nonlinear frequency technology was utilized for realizing the SHG6W-QCW-660nm output laser. And the characteristics of330nm UV laser were theoretically investigated.