Nonlinear Optical Effects In Optical Superlattices And Construction Of Optical Superlattices

With the development of modern Optics, more and more requirements are demanded in Laser. Nonlinear-frequency-conversion is one of the best ways in widening wavelength of Laser. At present, people usually use birefrigence and quasi-phase-matching methods to achieve higher effiency in the process of conversion. A significant advantage of quasi-phase-matching method is that the interaction is occurred through the largest element of the x (2) tensor; the period of optical superlattice can be designed randomly, and any interaction can be matched without walk-off angle; they are fitted to be used in frequency conversion of lower power especially. The quasi-phase-matching method has some advantages over birefrigence method, improving the efficiency of frequency conversion; the range of frequency conversion covers its whole transperant wavelength. Quasi-phase-matching method has been becoming one of the researching focus. At present, we have achieved frequency conversion in pulse-wave and continue-wave as well as quasi-continue-wave by using quasi-phase-matched method. In addition, quasi-phase-matched materials is being used in optical parametric oscillator widely. Periodically poled nonlinear crystals are of particular advantage for realizing efficient optical parametric oscillators. In this thesis,the main contents are following:1.Reviewing the theory of nonlinear frequency conversion.Quasi-phase-matching is discused. Presenting the method for configuring periodically poled as well as multiple period superlattice.2.Second harmonic generation in superlattice is derived from the coupled equation of three waves i discusing the relationship between the period of PPLN and pumping wavelength.3.On the theory of optical parametric oscillators, PPLN-OPO are analyed. Theoretical analysises on temperature tuning and period tuning are presented. The experiment of 1064nm pumped multi-periods PPLN-OPO was conducted. The experimental results are fit well with theoretical calculation.4.Reviewing different methods for constructing optical superlattice . Parameters are designed for constructing PPLN used for the second harmonic generation of 1064nm pumping wave.