LD Pumped All-Solid-State Blue Laser

A laser-diode- (LD) pumped solid state quasi-three-level Nd³⁺ laser with intracavity frequency-doubling has proved to be an efficient way to achieve the bule laser emission and has attracted more and more attention at present. It is due to its inherent advantages, which are characterized by its high output power, high quality of laser beam and low price. So far, however, the development is still not perfect in multiwatt level all-solid state blue laser. In this thesis, we perform some theoretical and experimental researches and gain some valuable results.Firstly, we analyze the theory of quasi-three-level system and demonstrate some parameters for optimizing the laser operation. Using numerical caculation, we analyze the influence of mode overlapping on the threshold pump power, slope efficiency and relationship between input and output power in order to provide a good testimony for the actual work. As a result, we caculate and obtain the optimization length of the laser crystal.Secondly, we introduce the principle of the frequency doubling technic and point out the points that must be noticed while using this technic. We also introduce the influence of phase-mismatch and the ways of achieving phase-match. After comparing some cyrstals we choose the LBO as the frequency doubling crystal in our design and introduce the attributes of it.Thirdly, the coupling lenses are designed using the ABCD theory. There is an optimization radius of pumping beam while laser operating. But the radius of pumping beam is divergent out of the fiber, so the pumping beam must cross a group of lenses and refocus before it enter laser crystal. We use the ABCD theory to analyze the coupling system, and point out how to adjust the parameters of the lenses to make the radii of pumping beam optimized.Analysing the cavity, we propose a method of measuring the focus length of themal lens. The themal lens focus lengthes of the Nd:YAG crystal with different pump power are measured by this way. In order to simplify cavity analysing, a new concept, inverse optical distance, is brought forward in this thesis. The stability of laser cavity is analysed to guide the variation of the cavity parameters. The position of the beam waist where the LBO will be placed is obtained. We also obtain the variation of the beam radii in the cavity with the themal lens focus length and the curvature radii of the ouput mirror.According to the upper Analysis, we design out a LD pumped all-solid-state blue laser, with 1.2W/473nm maximal output power. As far as we known, it is the highest output power at present in the line cavity.