Abstract
Using high voltage could make a periodically poled crystal, and the QPM(quasi-phase matching) technique not only expands the applications in many domains but also enlarges the conversion efficiency of the non-linear optics. The infra red which produced by the QPM-OPG could apply to the military, medical treatment, environmental monitor and long distance measurements…etc. The dissertation was devoted to fabricating periodically poled Lithium Tantalite(PPLT) and Lithium Niobate crystal. For producing high energy infra red, we choose the Lithium Niobate which has more great non-linear optical coefficient and we try to fabricate 1mm thickness PPLN. Connecting a resistance to limit the poling current, and we utilized two stages methods to fabricate PPLN crystal. Not only one overcame the problems during high voltage poling (~22kV) and collected many valuable parameters. We had succeeded in fabricating 40mm-long, 5mm width and 1mm thickness PPLN with period 29.6 um. Owing to the damage threshold of single PPLN crystal is too low to pump more energy, we try to combine staked PPLNs with micro-lens array to produce more energy of the infra red. The large energy pumping will be separated into many individual pieces by micro-lens array and incidents in the different location of cross section on PPLN. In OPG experiment, at 12 mJ pump pulse energy, it generated 2.8mJ pulse energy of the signal. Considering no AR coating and the loss of the reflector, the total conversion efficiency is about 30%.