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Semiconductor Laser-pumped Passively Q-switched Mode-locking Experiments And Theoretical Research

Posted on:2012-05-12Degree:MasterType:Thesis
Country:ChinaCandidate:H J ZhangFull Text:PDF
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Laser diode-pumped all-solid-state lasers, which have been paid much attention on during recent years, have a wide applications in many fields such as materials processing, military, medical, space communications, light display , optical interconnection, information processing and scientific research fields, laser telecommunication, light display et. al because of their compact structure, high efficiency, small heat effect, high stability, long life-time, high beam quality, wide wavelength range and various running modes.Comparing with actively Q-switched and mode-locked lasers, passively Q-switched and mode-locked ones, which do not need any exterior driving device, are of simple structures. During recent years, the theory and experiment research of the slow saturable absorber Cr4+:YAG with excellent physical and chemistry properties tended to be mature in generating high-frequency impulse in infrared laser. Cr4+:YAG has already been widely applied in CW-pumped passively Q-switched green lasers. In this thesis, the theory and experiment research of the intracavity frequency doubling passively Q-switched green laser and mode-locking characteristics of Cr4+:YAG crystal are mainly carried on, which mainly includes:1. The progress of all-solid-state laser is introduced; the introduction of the fundamental principles and the classification of Q-switched and mode-locked laser; the summary of the characterizations of different types of Q-switch and mode-lock technology is given.2. Introduction of the characters of Cr4+:YAG crystal. The fluctuation mode and the fundamental physical process in the passively mode-locking process were simply introduced. Discussion and analysis of the energy level and the main transition of the Cr4+:YAG crystal. By basic rate equations the dynamic process of saturable absorption in Cr4+:YAG is described. Analysis of the conditions that the Cr4+:YAG operates on Q-switched or mode-locking. Then the value of the saturable light intensity of the second excited state is calculated.3. Regarding frequency doubling process as an intracavity loss which changes with the transformation of the fundamental photon number, a couple of rate Equations describing the passively Q-switched intracavity frequency doubling green lasers are given, and the four-level nonlinear rate equation of passively Q-switched green laser is summarized. The theoretical analysis accords with the experimental results excellently.4. The LD-pumped Cr4+:YAG passively Q-switched and mode-locked laser is theoretically analyzed, and the output characteristics of the laser is researched. Using the passively Q-switched and mode-locked model, a couple of rate equations describing the passively Q-switched and mode-locked laser with Cr4+:YAG are given.
Keywords/Search Tags:saturable absorber Cr4+:YAG, intracavity frequency, rate equation, green laser, passively Q-switch and mode-lock
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