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Theoretical And Experimental Studies Of The Generation Of All-Solid-State Multi-Wavelength Femtosecond Laser

Posted on:2002-08-12Degree:DoctorType:Dissertation
Country:ChinaCandidate:J T BaiFull Text:PDF
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In this thesis, the development history process of all-solid-state lasers is reviewed in Chapter 1 firstly. The main characters of diode-laser pumped solid-state laser and all kinds of LD-pumped crystal material characters are introduced. The research evolution of LD pumped different wavelength all-solid-state lasers domestically and abroad has been summarized. The prospect of all-solid-state lasers is forecasted. In the Chapter 2, the basic model and work principle of LD-pumped all-solid-state lasers are induced. The oscillation threshold of four-level system , working slope efficiency and working point condition are deduced from rate equation theory. Also three-wave-coupling-theory and intracavity frequency-doubling nonlinear process are described. In the Chapter 3, all-solid-state two-end-pumped Nd:YVO4/KTP(LBO) laser technique is described. The infection of stability under high power pumped thermal lens effect, how to optimize thermal stability cavity configuration and cavity parameter are given. In the Chapter 4, all kinds of gain mediums of all-solid-state femtosecond laser and their characters are mainly induced. Theory analysis and experiment research of all-solid-state infrared femtosecond laser are studied. In the Chapter 5, the second harmonic generation (SHG) theory of femtosecond laser is introduced. The compensating of phase mismatching in doubling-crystal is analyzed and calculated by using spectrum spatial chirp of prism series. The experiment is carried out for all-solid-state Ti:S femtosecond blue and ultraviolet lasers. In the final chapter, thepivotal technique for the generation and amplifier of all-fiber femtosecond laser pulse is studied. The mechanism and pivotal technique of self-start-mode-locked andlaser pulse soliton compress effect are solved by theory and experiment. Concrete research contents and innovation as follows:1. The characteristics of input and output in the case of stable condition is obtained by introducing distributive function of end-pumping field and oscillating field in the theory. Not only pumping threshold and slope efficiency depending on the focus position of pumping light, but also the optimal spot size and efficiency of permeation are analyzed. The theory of intracavity frequency-doubling also is investigated. In addition, we have discussed several elements affecting the efficiency of frequency-doubling such as phase mismatch and walk-off effect etc. The stability of thermal cavity duo to high-power LD pumping is discussed particularly. After numerical simulative calculating, some elements such as cavity length and waist size that have some influence on the stability of cavity are analyzed. It has a certain significance for optimizing the configuration of cavity, choosing the parameter of light path and guaranteeing the high-power green laser output.2. Two LDs which have 12W output power and 810nm wavelength are used as the pump sources of intracavity frequency-doubling Nd:YVO4 laser. High stable configuration of non-sensitive for thermal laser cavity is designed according to numerical calculation. Thus laser can operate stably with thermal lens focus length between 5mm and 1000mm in the cavity. So a kind of all-solid-state green laser used as pump source of Ti:Sapphire laser is developed successfully.3. In order to decrease the threshold and to improve the light-light conversion efficiency of the Ti: Sapphire laser, we make numerical simulation in the Ti:S laser oscillator with the standard ABCD matrix and design an low operation threshold and high conversion efficiency femtosecond laser system. A femtosecond infrared laser averageoutput power of 300 mW is obtained with the pump green laser power of 2.5 W.4. In the case of femtosecond blue and ultraviolet laser, the mechanism of femtosecond laser second harmonic wave generation with nonlinear crystal is researched in theory. Owing to the wide bandwidth (usually between 50nm and 120nm )of femtosecond laser, the optimal phase matching could not be obtained(during such wide bandwidth...
Keywords/Search Tags:Diode-laser-pumping, Nd:YVO4 crystal, KTP, LBO, Green laser, Ti:Sapphire, Femtosecond blue pulse, Femtosecond ultraviolet pulse, Femtosecond fiber laser, Self-start-up, Soliton compression, Femtosecond fiber laser amplifier
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