| Mid-infrared laser is of high importance for many applications in the fields of optoelectric countermeasures, environment monitoring, spectroscopy, medicine, remote sensing and so on. Optical parametric oscillator is one of the most important methods to obtain the mid-infrared laser. It has widely tunable range, simple structure, high efficiency, high power, and high reliability. In recent years, with the development of new technology for nonlinear crystal, especially the periodically poling technique, many important breakthroughs have been made in the research field of optical parametric oscillator. In this thesis, the main work is based on the periodically poled MgO doped lithium niobate crystal (PPMgLN). The thesis is composed of the following research work:the high-power mid-infrared laser and the dual-wavelength mid-infrared laser for dual-end differential absorption laser system.High power mid-infrared laser requires a linearly polarized high power pump laser with good beam quality. In this thesis, we designed a double-end pumped Nd:YVO4 solid state laser as the OPO pump source. The Nd:YVO4 laser delivered a linearly polarized pulsed output emission at 1064 nm with an average power of 23.5 W at a repetition rate of 25 kHz. The beam quality factor (M) was about 1.9. With the Nd:YVO4 laser as the pump source a PPMgLN-based OPO was developed and a mid-IR laser output of 3.54 W at 3.82μm was obtained. The instability of the laser output was less than 4% while working normally under water cooling.We also demonstrated a dual-wavelength mid-infrared laser based on a cascaded PPMgLN, which was mainly for gas detection. A maximum average output power of 2.03 W was obtained from a laser diode-pumped solid-state laser at the repetition rate of 30 kHz. With the solid-state laser as pump source, dual-wavelength mid-infrared laser output was realized. The laser wavelengths were centered at 3.14μm and 3.34μm respectively and the total mid-infrared laser power is 200 mW. |
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