Characterization Of Diode-pumped Nd: KGd(WO₄)₂ Lasers

Pulsed lasers have been used widely in various fields, such as optical communication, medical, materials processing and nonlinear optics. Diode-pumped solid-state lasers have various advantages such as high conversion efficiency, long lifetime, compactness and high stability. Consequently, developing techniques for Q-switching or mode-locking in diode-pumped lasers has been burgeoning as a new exploration to get compact pulsed lasers.All-solid-state lasers, using synthetic crystals as basic materials , has rapid development of high power, multi-wavelength, wide tuning, long life and high stability.Laser crystals are the core of the lasers and determine the efficiency of lasers and various aspects of performance. Exploration for LD-pumped laser crystals is one of the main research fields of laser materials. In this dissertation, we discussed the technologies of acoustic-optical(AO) Q-switched, passively Q-switched, passively Q-switched and mode-locked,double Q-switched and AO Q-switched green laser properties in diode-pumped Nd:KGW microchip lasers. The experiment proved that this crystal has a vast application field.The main contents can be summarized as follows:1. The history,development and present conditions of diode pumped all-solid-state lasers are reviewed. Laser characterizations of Nd:KGW are introduced. The major researches we have made are summarized.2. Characterization of LD-pumped Nd:KGW active Q-switching and passive Q-switching laser. Basing on the theory of AO Q-switching, passive Q-switching, the properties of LD diode pumped 1064nm laser with short pulse duration are analyzed, laser pulse with short pulse duration and high peak power is obtained.3. Characterization of LD-pumped Nd:KGW passively Q-switched and mode-locked laser. A diode-pumped passively Q-switched and mode-locked Nd:KGW/ Cr⁴⁺:YAG laser with different output couples is firstly realized in a V-type folded cavity. About 85 % modulation depth for the mode-locked pulses has been obtained. An analysis of the temporal shape of a single Q-switched envelope with mode-locked pulse trains is presented. 4. Characterization of LD-pumped Nd:KGW double Q-switched laser. Diode-pumped AO Q-switched, passively Q-switched and double Q-switched Nd:KGW lasers were realized, respectively. Their pulse characteristics were researched. Experiments prove double Q-switching laser can generate a symmetric and shorter pulse when compared with purely AO and passive Q-switching. The double Q-switched laser pulse width of 37.7 ns has been achieved at the incident pump power of 3W.5. Characterization of LD-pumped Nd:KGW frequency doubling laser. Intra-cavity frequency doubling CW laser was researched by using a simple plano-concave cavity and KTP. And diode-pumped Nd:KGW AO Q-switched green laser was realized for the first time, to our knowledge by using AO modulator. Pulse widths, pulse energies and peak powers are measured at different repetition rates and pump powers. Pulse width of 30.6ns,pulse energy of 22.8μJ,peak power of 671W are obtained at the incident pump power of 2.9W and the repetition rate of 10kHz.