Research On Thermally Boosted Pumped Nd:yvo₄ Laser From The High Stark Sublevel Of The Ground State

The thermal effect is the bottleneck of the operation of solid-state lasers with high power, high efficiency, and high beam quality. According to the mechanism of the heat generation in solid-state lasers, the most fundamental way to deal with the thermal effect is to reduce the quantum defect between a pump photon and a laser photon. The thermally boosted pumping from the high Stark sublevel of the ground state is to pump the active ions from the high Stark sublevel of the ground-state level directly to the sublevel of the upper lasing level without a relaxation process and it can reduce the quantum defect to the minimum and eliminate the quantum efficiency loss, increase the quantum efficiency and reduce the heat generation to a greatest extent, which makes it become an ultimate technology to deal with the thermal effect.In this dissertation,using an all-solid-state quasi-continous tunable Ti:Sapphire laser and a continues 914 nm Nd:YVO₄ laser, respectively, as the pump source, the impact of the temperature, the doped concentration and the length of the laser crystal on the thermally boosted pumped Nd:YVO₄ laser from the high Stark sublevel of the ground state is to be researched. The main contents and key creation points are as follows:1. The characteristics of the thermally boosted pumping in Nd:YAG and Nd:YVO₄ crystal were introduced. And the thermal effect of the end-pumped solid state lasers was theoretically researched. Based on the rate equations of four-level system, the mechanism of the thermally boosted pumping was studied.2. High power all-solid-state quasi-continuous widely tunable titanium-doped sapphire laser was experimentally researched. The tuning range from 675 to 970 nm with the linewidth of 2 nm and the pulse width of 17.6 ns was obtained. The maximum output power of this laser system was 6.2 W at 780 nm corresponding to all optical-to-optical conversion efficiency of 28.2%. And the output power at 914nm is 3.7 W.3. The physical model and time properties of the gain-switched solid state lasers was theoretically researched. The Nd:YVO₄ laser under 914nm thermally boosted pumping by the Ti:Sapphire laser was experimentally researched. A high slope efficiency of 79% and pulse width of 3.1 ns were obtained, which is the verification of the gain-switching effect of the Nd:YVO₄ laser.4. Based on the experiment of continuous 914nm thermally boosted pumped 1064nm and 1342nm Nd:YVO₄ laser from the high Stark sublevel of the ground state, the impact of the temperature, the doped concentration and the length of the laser crystal on the output characteristics of the laser was reasearched. When the temperature of the crystal was 50oC, a maximum output power at 1064nm of 2.2W was achieved in a 1.0 at.% Nd:YVO₄ crystal with the dimension of 3 mm×3 mm×10 mm, leading to a high slope efficiency of 83.9%. In two 1.0 at.% Nd:YVO₄ crystals with the dimension of 3 mm×3 mm×4 mm, a maximum output power of 1.05W and a high slope efficiency of 66.4% were obtained at 1342nm.