Improved Design Of Aperiodically Poled Crystals And Experimental Study On Quasi-phase-matched Intra-cavity Frequency Doubling

The main content of this dissertation is that the improved design of aperiodicallypoled crystals based on simulated annealing (SA) algorithm and experimentaldemonstration of intra-cavity frequency doubling by use of quasi-phase-matched (QPM)technique. There has been a growing interest in the QPM technique because of its prominentproperties. QPM nonlinear optical frequency conversion has the advantage of especiallyhigh conversion efficiency for a variety of applications since the 1990s with thedevelopment of electrical poling method. The mostly trend of the QPM technique is to take the advantage of flexibility in thedesign of the crystal patterns. In principle we can obtain coupled outputs of arbitrary twoor more nonlinear optical processes such as high order harmonic generation, tunablecoherent source and multiple wavelength coherent radiation through the proper design,which can reduce the wavelength conversion procedures and simplify the optical system. By employing all-solid-state intra-cavity frequency doubling configuration, theeffective green laser radiation can be obtained which has the compact structure and highconversion efficiency. Here, we report the experimental study of QPM intra-cavityfrequency doubling.There following innovation points:1. By choosing appropriate parameters we obtain better structures to realize multiplewavelengths frequency doubling and optical parameters amplification(OPA) whilethese wavelengths separate only tens nanometers.2. It is indicated that conversion efficiency equation of frequency doubling can insteadof the gain formula of OPA in the objective function to save calculation time.3. We present the design examples of coupled outputs of the nonlinear opticalfrequency up-conversion and down-conversion.4. We report the intra-cavity frequency doubling based on PP-MgO:SLT with thedimensions of 20×10×1mm~3, the optical-optical conversion efficiency is 19% andthe maximum output is 2.1W while the pump power is 11W.