Study On 473nm All-Solid-State Blue Laser

At present, LD-pumped solid state lasers (DPSSL) have been developed as one of vital domain in laser field. Furthermore, DPSSL have gradually replaced the traditional laser, which is mainly attributed to its perfect development and its wide applications, such as material processing, medicine, military and so on.LD-pumped Nd3+ lasers with intracavity frequency-doubling have proved to be a most efficient and commercial-potential way to achieve the blue laser emission and have attracted more and more attention in recently years. So far, however, the development is still not perfect in watt-level all-solid state blue laser. In this thesis, some theoretical and experimental investigation on continuous wave diode pumped intracavity doubling Nd:YAG blue laser at 473nm have been performed, which will be expected to be useful for commercializing such blue lasers.This thesis is organized as follows:1. For the very beginning, the physical and optical characteristics of Nd:YAG and Nd:YVO4 laser crystals have been introduced. Comparing both of their advantage and disadvantage over quasi-three-level transition, we finally adopt Nd:YAG crystal as our laser medium in our blue laser. After investigating in details on the properties of quasi-three-level system of Nd:YAG, we show that the temperature control of laser crystals (Nd:YAG) is vital for obtaining the 946nm lasing.2. we introduce the theory of second-harmonic generation in nonlinear crystals and provide the feasible ways to increase the frequency-doubling efficiency. By comparing those popular frequency-doubling crystals, the outstanding nonlinear crystal, LBO, is adopted in our work. Specifically, the physical and optical properties of LBO are emphasized. Furthermore, the frequency-doubling principle in a LBO crystal at type-I phase matching is also illustrated.3. A few of different resonant cavities for diode pumped intracavity frequency-doubling blue lasers are given. Based on the ABCD theory, the important parameters of cavity-modes are obtained, and then the cavity design rules have been pointed out. In addition, using the plan-plan cavity, the thermal lens focus lengths of the Nd:YAG crystal with different pump power are measured, which has some value in cavity design.4. Based on the cavity analysis, we finally use the plan-concave cavity in our experiments. Using LD-end-pumped Nd:YAG, LBO intracavity frequency-doubling and air-cooling, we demonstrate an output power of 1.6 W at 473nm and optical-to-optical conversion efficiency 7.8% blue laser. To the best of our knowledge, this is the highest output power obtained in linear-cavity blue laser at present. Moreover, we also analyses the obtained experimental results and give out the drawbacks in our experiments.5. Designing a V-type folded cavity and optimizing the cavity parameters, we obtain the output power of 421mW/473nm blue lasing. The potential reasons that the output power is not ideal have been discussed and the improvements have been also given.