Self-Raman Frequency Conversion Of The Third-order Stokes Laser Of Nd:YVO 4 Composite Crystal

Stimulated Raman scattering(SRS) is a practical and efficient nonlinear frequency conversion method. All-solid-Raman lasers based on the Raman crystals can expand the laser spectrum from ultraviolet to near infrared. The all-solid-state Raman lasers have become the research focus in the field of lasers with the advantages of compactness, high efficiency, high stability. The all-solid-state self-Raman lasers have wide applications in medicine, measurement, national defence, and so on.The output power of solid-state laser, especially the self-Raman solid-state laser is restricted by the thermal effect of solid-state laser. The approach in particular advantages in the self-Raman laser as the composite vanadate crystal can not only reduces the thermal effects of laser crystal but also increases the interaction length for SRS. In the dissertation, composite Nd:YVO4 crystal has been used.In this paper, we made experimental research on the characteristics of the Laser-Diode-end-pumped, acousto-optical Q-switched(AOS) third-Stokes self-Raman laser output with the different pulse repetition rates(PRFs) and different resonant cavity structures, by employing the fiber-coupled laser-diode(LD) as the pump source, Nd:YVO4 composite crystal as the laser materials. By using of AOS and the self-Raman effect of Nd:YVO4 composite crystal, the simultaneous Q-swithched and mode-locked(QML) third-Stokes(1487 nm) self-Raman lasers have been achieved.The main contents of this thesis are as follows:? By employing composite Nd:YVO4 crystal and acousto-optic Q-switched, the third-Stokes self-Raman laser at 1487 nm was researched on different PRFs and resonant cavity structures. Based on different types of cavities, we did experimental research on the characteristics of the third-Stokes self-Raman laser at 1487 nm. The maximum output power of second-Stokes Raman laser were measured to be 695 mW and 763 mW at different resonator cavities, with the corresponding optical conversion efficiency of 2.67% and 2.38%, respectively. With plano-concave cavity, the minimum pulse width, the maximum single pulse energy, and the peak power were obtained to be 1.041 ns, 37.34 ?J and 31.3 kW, respectively.? We did experimental research on the characteristics of the simultaneously Q-switched and mode-locked third-Stokes self-Raman laser at 1487 nm. The maximum output power of the QML self-Raman laser was measured to 588 mW at the incident pump power of 24 W and the PRF of 25 kHz, with the corresponding optical conversion efficiency of 2.45 %. The shortest mode-locked pulse width, the biggest single pulse energy and the peak power were obtained to be 21.09 ps, 8.23 ?J, and 390 kW, respectively. The M2 factor were measured to be 2.23 along the X axis and 2.88 along the Y axis, respectively, at the maximum output power.