Research On Collinear Quasi-Phase Matched Optical Parametric Process

Quasi-phase matching (QPM) technique is an important component in nonlinear optical frequency conversion. It aroused the interests of scientists due to the advantages of high conversion efficiency and flexible tuning methods. The collinear QPM optical parametric process (including optical parametric oscillator, OPO and optical parametric generator, OPG) is a promising scheme to achieve the tunable coherent light source. The collinear QPM-OPO/OPG can accomplish many goals, which is difficult to the conventional birefringent phase matching. More suitable tunable light source based on collinear QPM-OPO/OPG emerged for many other scientific researches and applications. The work in this dissertation focused on the tunable dual wavelength laser, near-infrared laser, mid-infrared laser, and narrow-linewidth laser based on collinear QPM-OPO and QPM-OPG. These laser sources could be applied in many applications such as gas detection, pollution monitoring, military infrared countermeasure, optical communication, scientific research and so on.The main contents and key creation points in this dissertation are as follows:1. A concept of backward grating vector was proposed theoretically and the tuning character of -1 order quasi-phase matched process was discussed. Then, we summarized the collinear quasi-phase matched optical parametric process and analyzed the period tuning characters;2. Dual signal-wave QPM-OPO was investigated experimentally and theoretically. The condition of the dual signal output with the same ratio was discussed with consideration of the influence of the focal point position. There were two periodically poled crystals in the experiments, which shared the same resonant cavity. The wavelength interval of 2.5nm~69.1nm could be tuned by adjust the temperature and the period. At the repetition rate of 50 kHz, the maximum dual signal average power was 169.6mW with the incident power of 3W. To our knowledge, this is the first time to apply the periodically poled crystals in dual signal-wave QPM-OPO;3. The seed-injected collinear QPM-OPO was presented experimentally. At first, the diode pumped 1064nm Nd:YVO4 laser based on ring cavity was investigated as the pump source of the OPO. The CW output power of 9W was obtained in the experiment and the corresponding efficiency was 36.6%. An acousto-optic Q-switch was inserted to achieve high peak power. Pumped by this laser, a seed-injected narrow-linewidth QPM-OPO can provide 1510nm~1630nm tunable laser with the maximum average power of 56.9mW and the linewidth of 0.06nm;4. The diode pumped intra-cavity QPM-OPG was studied experimentally and theoretically. The dynamic characters and output characters of intra-cavity OPG were analyzed theoretically, according to the three-wave coupled equations and acousto-optic Q-switched four-level rate equation. We used Nd:YVO4 as gain medium and PPLN as nonlinear crystal in the experiments. The tunable laser between 1.497~1.517μm with the maximum average signal power of 330mW was obtained, and the corresponding efficiency from diode power to signal power was 5.5%;5. The room-temperature mid-infrared QPM-OPO based on PPMgLN was demonstrated experimentally. The mid-infrared coherent light over 1W was achieved with the conversion efficiency of 26.7%.