Pulsed1.1Micrometer And Continuous-wave1.5Micrometer All-solid-state Raman Laser

Stimulated Raman scattering (SRS) is an effective method to generate new wavelengths based on frequency conversion. SRS belongs to the third-order nonlinear optical effect, and the wavelength of the scattered light is determined by the wavelength of the pumped light and the Raman shifts of the Raman-active media. By selecting different pumping sources and Raman-active media, the laser spectrum reachable with SRS can extend from the ultraviolet to the near infrared, which greatly widened the laser spectral range. Raman-active media as the key part of Raman laser include gases, liquids and solids. The solid-state Raman-active media has become the most common Raman-active media because of the advantages of high Raman scattering gain, high molecule density, favorable thermal and mechanical properties, narrow linewidth of the vibrational modes, and the compatibility with the compact laser technology. The all-solid-state Raman lasers based on crystalline Raman media take advantages of high efficiency, compactness and high stability, which make it have wide applications in such fields as military affairs, medical treatment, communication, information, agriculture and so on.All-solid-state Raman lasers can be used to generate infrared lasers directly or generate visible light combined with frequency conversion technology. The main studying aspects of all-solid-state Raman lasers are (1) By using1.06μm or1.3μm laser as pumping source, combined with Q-switched or mode-locked technology to generate1.18μm or1.5μm pulsed Raman laser.(2) Combined pulsed Raman laser with different second-order nonlinear optical effects (frequency doubling, sum frequency and optical parametric oscillation) to obtain diverse wavelengths.(3) By selecting Raman media with high Raman gain coefficient and optimize Raman cavity to dismiss losses of Raman laser to obtain continuous-wave Raman laser operation. So far, the research of pulsed Raman laser has become more mature, but the reports of continuous-wave solid-state Raman laser are not many. The continuous-wave eye-safe solid-state Raman laser based on stimulated Raman Scattering has not been reported.In this master thesis, by using Nd:YAG and Nd:YVO4as the gain media, BaWO4and BaTeMo2O9as the Raman-active media, we make a detailed experimental study of the LD end-pumped Q-switched and continuous-wave intracavity Raman lasers. The main contents of this dissertation are as follows:1. A compact BaWO4Raman laser is realized with a diode-end-pumped acousto-optically Q-switched YVO4/Nd:YVO4laser. Based on the Raman shift at332cm-1of BaWO4, first-Stokes generation at1103nm is generated. At a pump power of11.3W and a repetition rate of45kHz, an average power of1.59W is obtained which is the highest average power based on Raman shift at332cm-1of BaWO4. The corresponding Diode-to-Stokes optical conversion efficiency is14%. The pulse width is measured to be36.8ns and the beam quality factor (M2) in the horizontal and vertical directions are determined to be1.56±0.1and1.41±0.1, respectively. The thermal focal lengths of the laser medium and Raman medium decreased from926mm to457mm and from-8259mm to-1241mm with the pump power increasing from6.2W to11.3W at45kHz.2. A diode-end-pumped passively Q-switched intracavity Raman laser at1179nm is obtained with the BaTeMo2O9nonlinear Raman crystal for the first time. With an incident pump power of12.3W, the average output power of1179nm is obtained to be0.41W. The pulse repetition rate is measured to be24kHz and the pulse width is5.2ns. The beam quality factors (M2) in the horizontal and vertical directions are determined to be1.5±0.1and2.0±0.1, respectively.3. A continuous-wave eye-safe Raman laser employing Nd:YVO4as gain medium and BaWO4as Raman medium is demonstrated. The Raman threshold is as low as1.8W of diode power at808nm. The highest output power obtained at the1532nm first-order Stokes line is102mW under the incident diode pump power of9.1W.4. A continuous-wave eye-safe self-Raman laser at1525nm in a double-end diffusion-bonded Nd:YVO4crystal is demonstrated for the first time. The maximum output power obtained at1525nm first-order Stokes is156mW under the incident diode pump power of17.5W.