Study On Performance Of All-solid-state 1.34μm And Frequency-doubled Nd:Gd_0.63Y_0.37VO₄ Laser

In recent several years, there has been an increasing interest in laser-diode (LD) pumped all-solid-state lasers because such lasers can be widely used in the fields of military affairs, industry, medicines and so on. The wavelength of 1.34μm laser is identical with the low dispersion and low loss wavelength of silicon optical fiber. Therefore, it coincides with the transmission window of silicon optical fiber and the frequency-doubling of these lasers supplies an effective way to generate red lasers. So there are widespread application fields for the lasers operating nearby 1.34μm in laser medicine, optical fiber communication, optical sensing locating and the pump source of mid-infrared optical parametric oscillation.Nd:Gd0.63Y0.37VO4 is a new one in the class of Nd-doped mixed vanadate crystals. It has been proved to be a good laser gain medium for 1.06μm Q-switched operation. In my study, we have analyzed the Nd:Gd0.63Y0.37VO4 laser performance experimentally and theoretically, and for the first time, measured the thermal focal length and passive loss of Nd:Gd0.63Y0.37VO4 crystal. By fiber-coupled laser-diode being used as the pump source and V3+:YAG saturable absorber as the Q-switch, the Nd:Gd0.63Y0.37VO4 laser with wavelength of 1.34μm and Nd:Gd0.63Y0.37VO4 red laser with wavelength of 0.67μm have both been realized. Through the experimental research, we get the excellent characteristics of Nd:Gd0.63Y0.37VO4 crystal as laser medium in this paper.The main contents of this dissertation include:1. The thermal focal length and passive loss of Nd:Gd0.63Y0.37VO4 crystal have both been researched;2. The LD-pumped CW characteristics of Nd:Gd0.63Y0.37VO4 laser at 1.34μm have been researched;3. Using short plane-concave cavity, we have got the characteristics of the LD-pumped passively Q-switched Nd:Gd0.63Y0.37VO4 laser with V3+:YAG saturable absorber at different output transmissions. With the V3+:YAG initial transmission of 96%, the pump power of 5.04W and the output transmission of T=5%, the shortest pulse with width of 61.4ns is obtained. By using the rate-equation theory, we have analyzed the laser performance and the theoretical calculations agree with the experimental data;4. Using plane-concave cavity, we have got the characteristics of the LD-pumped actively Q-switched Nd:Gd0.63Y0.37VO4 laser with AO modulator at different output transmissions and different modulation repetition rates. With the modulation repetition rate of 10kHz, the output transmission of T=5%and the pump power of 4.45W, the actively Q-switched pulses with the shortest pulse width of 45.6ns, the largest single pulse energy of 32.6μJ and the highest peak power of 715W are achieved;5. With the three-mirror-folded laser cavity, the CW output characteristics of the LD-pumped Nd:Gd0.63Y0.37VO4/KTP 0.67μm red laser are given;6. With the three-mirror-folded cavity, we have got the characteristics of the LD-pumped passively Q-switched Nd:Gd0.63Y0.37VO4/KTP red laser with V3+:YAG saturable absorber. When the V3+:YAG initial transmission To is 89%and the pump power is 4.1W, the shortest pulse width of 125ns with the largest single pulse energy of 4.3μJ and the highest peak power of 34.4W is obtained. The theoretical calculations of the rate equations are consistent with the experimental results.The main innovations of this dissertation are as follows:1. We firstly research the thermal focal length and passive loss of Nd:Gd0.63Y0.37VO4 crystal;2. Using LD end-pumping, we have experimentally and theoretically studied the performance of the passively Q-switched Nd:Gd0.63Y0.37VO4 laser with V3+:YAG saturable absorber in a planar-concave cavity for the first time, and the theoretical calculations are accord with the experimental data;3. With the three-mirror-folded cavity, we firstly present the performance of the LD-pumped intracavity-frequency-doubling Nd:Gdo.63Yo.37V04/KTP 0.67μm red laser operating in CW regime, as well as in the passive Q-switching regime with V3+:YAG, respectively. We have also given the rate-equation model to analyze the laser characteristics and the theoretical predictions are in agreement with the experimental results.