1091nm And1178nm Solid-state Raman Lasers

Nonlinear optical frequency conversion technology is a reliable way to obtain new laser wavelengths for practical needs, it has great theoretical and practical value. It has been an important research area in the optical field. Stimulated Raman Scattering (SRS) is an effective method for laser frequency conversion, which could help to obtain high power of the output laser. SRS belongs to the third-order nonlinear effect, and the wavelengths of the generated Raman scattered light are determined by the pump laser wavelengths and the Raman shifts of the Raman crystals. By using different pump sources and different Raman-active media, the laser spectrum with SRS can extend from the ultraviolet to the near infrared area. The solid-state Raman lasers use existing laser pumping source and the SRS of many crystals to generate new laser lines. Solid-state Raman laser has the advantages of small size, good stability, high conversion efficiency, and have been widely used in the field of transportation, health care, information and defense.In this dissertation, we first studied the rate equations of LD end-pumped passivelyO-switched intracavity Raman laser, thenby using Nd:YAG laser as the pumping laser, we studied a LD-end-pumped passively Q-switched KTA Raman laser and a LD-side-pumped AO Q-switched CaWO4Raman laser, and studied their output laser characteristics. The main contents of this dissertation are as follows:1. Rate equations for end-pumped passivelyQ-switched intracavity Raman laser aretheoretically deduced and normalized by considering the cavity light field and the initial population inversion.andthe influences of the four main factors on the Stokes Raman laser output characteristics are analyzed with the mode-matchingof the cavity light field and pump laser.2. A diode end-pumped passively Q-switched Nd:YAG/KTA intracavity Raman laser is presented. A KTA crystal with a size of5×5×25mm3is used as the Raman active medium and its234cm-1Raman mode is employed to finish the conversion from1064nm fundamental laser to1091nm Raman laser. Nd:YAG and Cr4+:YAG are used as the gain medium and the saturable absorber, respectively. With an LD pump power of7.5W, the first-Stokes power of250mW is obtained with a pulse repetition frequency of14.5kHz. The corresponding diode-to-Stokes conversion efficiency is3.3%and the Raman pulse energy is17.2μJ. Raman pulse width is measured to be12.6ns and peak power is1.4kW.3. A LD-side-pumped Nd:YAG/CaWO4Raman laser is realized. Using Nd:YAG as the laser material and CaWO4as the Raman material, we realise a acousto-optically Q-switched intracavity Raman laser, the910cm-1Raman mode of CaWO4is employed to finish the conversion from1064nm fundamental laser to1178nm Raman laser. With a pumping power of90.9W and a pulse repetition rate of5kHz, we obtained2.58W of1178nm Raman laser power. The corresponding optical-to-optical (diode-to-Raman laser) conversion efficiency is2.84%. The corresponding pulse widths of the funmental and Raman lasers were144ns and70ns, respectively. The Raman peak power is7.37kW.