Laser diode-pumped all-solid-state lasers have a compact structure,high efficiency, small heat effect,high stability,long life-time,high beam quality,wide wavelength range and various running modes.Due to the advantages,these kinds of lasers have a wide range of applications in the fields such as materials processing,military,medical,space communications,light display,optical interconnection,information processing and scientific research fields,laser telecommunication,light display and so on.Laser crystal is the core component in laser system.Its physical and spectra properties determine the global design and output characteristics of the laser system.The Nd-doped crystals due to their excellent lasing property and availability of direct laser diode pumping have been widely used to construct compact laser-diode pumped solid-state lasers in the near-infrared region.In this dissertation,by using the fiber-coupled laser-diode as the pump source,Nd:YVO_{4},Nd:GdVO_{4},and Nd:LuVO_{4} crystals as the gain media,we have studied the performance of the passively Q-switched mode-locked(QML) lasers at 1.06μm and 1.34μm with Cr:YAG,LT-GaAs,SESAMs as well as V:YAG saturable absorbers,respectively.The research on the frequency doubling performance of the KTP crystal in the passively QML lasers has been carried out.Considering the Kerr-lens effect of Nd:GdVO_{4},the diode-pumped self-passively QML Nd:GdVO_{4} lasers have also been obtained and the characteristics have been studied.Using the cascading of second-order nonlinearities of KTP crystal, diode-pumped self-passively QML intracavity frequency doubled Nd:GdVO_{4}/KTP green laser is obtained.In addition,we studied the actions of acoustic-optic(AO) modulator in self QML Nd:GdVO_{4} laser,self QML Nd:GdVO_{4}/KTP green laser and QML Nd:GdVO_{4}/Cr:YAG laser,respectively.Meanwhile,the coupling rate equations under Gaussian wave approximation have been estabilished to theoretically analyze the properties of the above-mentioned QML lasers.The main contents of this dissertation include:ⅠThe principle of the simultaneously Q-switched and mode-locked lasers has been presented first,then using the indensity fluctuation mechanism and the rate equations model for the Q-switched lasers,the rate equations describing the simultaneously Q-switched and mode-locked lasers under Gaussian distribution approximation have been given.A diode-pumped simultaneously Q-switched and mode-locked c-cut Nd:GdVO_{4} 1.06μm and 0.53μm laser with Cr:YAG crystal have been realized in the experiment,and the dynamic process of such lasers have been simulated by using the proposed mode-locking rate equations model.(§2.2)ⅡUsing aⅤ-type cavity,a diode-pumped passively Q-switched and mode-locked Nd:GdVO_{4} 1.34μm laser with V:YAG crystal as the saturable absorber is realized.The characters of the laser have been studied.Using the passively QML model under Gaussian distribution approximation,a couple of rate equations describing the passively QML laser with V:YAG are given.The numerical solution is consistent with the experimental results. (§2.3)ⅢBy employing a 1.06 m three-mirror-folded cavity configuration,LT-GaAs as the saturable absorber,a diode-pumped passively QML Nd:LuVO_{4} 1.06μm and Nd:GdVO_{4} 0.53μm green lasers are realized.Considering the two-photon absorption of GaAs,a couple of rate equations under Gaussian distribution approximation describing the passively QML laser with LT-GaAs are given.And the dynamic process of such laser has been simulated by using the proposed mode-locking rate equations model.(§3.2)ⅣUsing SESAM as an intracavity saturable absorber,we obtained the performance of a diode-pumped passively Q-switched and mode-locked Nd:GdVO_{4} laser at 532 nm.Using the hyperbolic secant function methods,we have introduced a rate equation mode for the QML SESAM green laser,in which the Gaussian distribution of the intracavity photon lifetime of the active medium,the excited-state lifetime of the saturable absorber and the effective average loss of SESAM were taken into account.With this model,the theoretical evaluations are in good agreement with the experiments.(§3.3)ⅤA steadily self-Q-switched and mode-locked diode-pumped c-cut Nd:GdVO_{4} laser without inserting any additional intra-cavity element has been observed.Considering the Kerr-lens effect of laser medium and the soft aperture induced by the distribution of pump beam in the laser medium,we have analyzed the self-mode-locked c-cut Nd:GdVO_{4} laser by using the nonlinear ABCD propagation matrix and the hyperbolic fluctuation mechanism.The numerical solutions are in good agreement with the experimental results.(§4.2)ⅥConsidering the cascading of second-order nonlinearities of KTP crystal,and also the influences of Kerr-lens effect of laser crystal,a developed rate equation model for self QML lasers was proposed.A diode-pumped self a-cut and c-cut Nd:GdVO_{4}/KTP green laser is realized in the experiment,and the dynamic process of such laser has been simulated by using the proposed mode-locking rate equations model.(§4.3)ⅦUsing the AO modulator and considering the Kerr-lens effect of Nd:GdVO_{4} crystal and the turn-off time of AO Q-switch,a rate equation model under Gaussian distribution approximation describing the Kerr-lens QML laser is given.By using three-mirror-folded cavity,a diode-pumped Nd:GdVO_{4}/AO 1.06μm and Nd:GdVO_{4}/AO KTP 0.53μm green laser have been realized in the experiments.For different repetition rates,the laser properties such as average output power and pulse energy have been measured.The numerical solutions are in good agreement with the experimental results.(§5.1,§5.2)ⅧThe experimental studies on the diode-pumped doubly Q-switched and mode-locked Nd:GdVO_{4} laser with AO and Cr:YAG have been carried out.By inserting an acousto-optic modulator inside the laser cavity,the stability of the Q-switched and mode-locked Nd:GdVO_{4} laser was significantly increased.The laser properties when the AO modulator turn on and turn off were both reached.By considering the influence of the turnoff time and the modulation frequency of the acousto-optic modulator,we proposed a developed rate equation model for actively-passively Q-switched and mode-locked lasers.With this developed model,the theoretical calculations are in good agreement with the experimental results.(§5.3)The main innovations of this dissertation are as follows:ⅠWe firstly develop a rate-equation model for the diode-pumped under Gaussian distribution approximation,and we firstly realize the operation of the diode-pumped simultaneously Q-switched and mode-locked c-cut Nd:GdVO_{4} 1.06μm and 0.53μm with Cr:YAG saturable absorber.The numerical analysis is consistent with the experimental results.ⅡBy employing KTP as the frequency doubling crystal,we firstly study the experimental and theoretical operation of the diode-pumped simultaneously QML c-cut Nd:GdVO_{4}/KTP LT-GaAs green laser.Using a couple of rate equations describing the dynamic process of the QML green laser with LT-GaAs,and the theoretical simulation reconstructs the output pulse of the mode-locked laser.ⅢUsing the AO modulator,we firstly realize a steadily self QML diode-pumped Nd:GdVO_{4} laser.Considering the Kerr-lens effect of laser medium,the influence of the turnoff time and the modulation frequency of the acousto-optic modulator,we proposed a developed rate equation model for Kerr-lens QML lasers.With this developed model,the theoretical calculations are in good agreement with the experimental results.ⅣBy considering the cascading of second-order nonlinearities of KTP crystal and the Kerr-lens effect of laser medium in the dynamic process of the self QML laser,a rate equation model is build up to describe diode-pumped intracavity frequency doubling Nd:GdVO_{4}/KTP green laser operating in QML.The numerical analysis is consistent with the experimental results. ⅤWe firstly realize a diode-pumped actively-passively QML Nd:GdVO_{4} laser with Cr:YAG and AO modulator.Meanwhile,using the hyperbolic secant function methods and by considering the influence of the turnoff time and the modulation frequency of the acousto-optic modulator,we proposed a developed rate equation model for actively-passively Q-switched and mode-locked lasers.With this developed model,the theoretical calculations are in good agreement with the experimental results.ⅥWe firstly present systematically theoretical and experimental studies on the laser properties of diode-pumped Nd:GdVO_{4}/V:YAG 1.34μm laser operating in QML by using aⅤ-type cavity.Using the hyperbolic secant function methods,we have introduced a rate equation mode for the 1.34μm QML laser,in which the Gaussian distribution of the intracavity photon lifetime of the active medium,the excited-state lifetime of the saturable absorber are taken into account.With this model,the theoretical evaluations are in good agreement with the experiments. |