Study Of Frequency Tuning Techniques For LD Pumped Single Frequency ND:YAG Laser

Compared with the traditional solid-state laser,tunable single-frequency solid-state laser has a number of advantages such as good monochromaticity,small volume,high efficiency and low noise,as can be widely used in laser interference measurement,laser spectroscopy and other fields,and has become an important research direction in the field of all-solid-state lasers.The frequency tuning techniques of single frequency solid state Nd:YAG laser has been investigated in this thesis,which is of important significance and has broad application prospects.In this thesis,a birefriiigent filter consisting of both a splitting prism(PBS)as the polarizing component,which is used together with a birefringent crystal to form a birefringent filter so as to realize single longitudinal mode selection.Two kinds of frequency tuning schemes have been designed by using the birefringent crystal as the laser frequency tuning element.The principles of single longitudinal mode selection and frequency tuning have been theoretically analyzed,and the characteristics of oscillation and frequency tuning of single frequency Nd:YAG laser have been investigated experimentally.The main contents of this thesis are included as follows.Firstly,the research status of tunable single-frequency solid-state lasers at home and abroad has been briefly described.The basic composition and operation characteristics of LD-pumped Nd:YAG laser have been introduced.The priciple of single-longitudinal-mode selection by use of birefringent filter has been analyzed,and the LD-pumped 1064nm single-frequency Nd:YAG laser has been designed by using the birefringent filter consisting of both a PBS and a birefringent crystal.Secondly,iin the 1064nm single-frequency Nd:YAG laser system based on birefringent filter mode-selection principle,two kinds of frequency tuning schemes have been designed by using the birefringent crystal as the laser frequency tuning element,being named as crystal-axis self-rotated frequency tuning and crystal-axis-tilted frequency tuning.The principles of both kinds of frequency tuning schemes have been analyzed theoretically,and the tunable single-frequency Nd:YAG laser systems with self-rotated crystal axis and tilted crystal axis have been designed respectively,and corresponding feasibilities have also been analyzed.Thirdly,the experimental system of tunable single frequency Nd:YAG laser with self-rotated crystal axis has been established and the characteristics such as mode selection,frequency tuning,output power and laser polarization have been investigated experimentally.The experimental results have shown that the laser frequency can be tuned by rotating the birefringen crystal around its crystal axis,and the frequency tuning range is approximately 150GHz,but the laser polarization direction changes with the rotation of the crystal axis.Fourthly,the experimental system of tunable single frequency Nd:YAG laser with tilted crystal axis has also been established and the characteristics such as mode selection,frequency tuning,output power and laser polarization have been investigated experimentally.The experimental results have shown that the laser frequency can be tuned by changing the tilt angle of the birefringen crystal axis,and the frequency tuning range has been approximately 150GHz.With the tilted angle of the crystal axis increased,the laser frequency and the output power changed periodically,nevertheless the laser polarization direction remains unchanged.In a word,the frequency tuning techniques for the LD-pumped single-frequency Nd:YAG laser have been investigated deeply in this thesis,and two kinds of frequency tuning schemes have been designed,and both have a frequency tuning range of approximately 150GHz,as has laid a solid foundation on the research and development of LD-pumped tunable single-frequency solid-state lasers.