【作者】 赵军伟；

【导师】 朱永元；

【作者基本信息】 南京大学 ， 凝聚态物理， 2011， 博士

【摘要】 在过去的十几年里,随着准位相匹配材料研究的发展,由光学超晶格构成的全固体激光器得到了迅速的发展和广泛的应用。由于全固体激光器具有体积小,可靠性高等各种优点,越来越多的科研人员开始利用铌酸锂和钽酸锂晶体等优秀的光电功能材料来构造各种固体激光器,用以实现光学频率的转换。利用光学超晶格的非线性效应,对激光进行变频可以覆盖可见光波段及紫外和红外区域,基本上满足了日益发展的科研需要。并且超晶格具有增益高,阈值低及易于实现位相匹配等特点,已经成为了一种十分重要的激光变频材料。作为一款优异的光学材料,铌酸锂和钽酸锂晶体也具有出色的电光效应和声光效应,利用其电光效应和声光效应也可以对光进行控制,偏转和调整等。本文根据准位相匹配理论及晶体的电光效应,研究了一维周期、准周期结构中倍频的调控,研究了电光效应对周期结构中多参量耦合过程的调控,得到了有效的三次谐波的输出,研究了声光效应对周期结构中倍频的调控。论文的主要内容如下：1.以808nm半导体激光器为泵浦源,以Nd:YAG晶体为激光晶体,利用极化得到的铌酸锂周期结构和钽酸锂准周期结构超晶格,实现了1064nm输入激光的倍频调控,得到了532nm绿光的有效输出,通过调节外电场实现了倍频光的振幅和偏转控制。2.以808nm半导体激光器为泵浦源,以Nd:YV04晶体为激光晶体,利用极化得到的钽酸锂周期超晶格,实现了1342nm输入激光的多参量耦合过程中的电光调控。通过对1342nm倍频过程与和频过程的电光调控,我们得到了三次谐波输出的有效提高。3.研究了光学超晶格中的声光效应对光的调控。在周期超晶格倍频过程中,将声波引入超晶格中,将会影响倍频光的偏振态,进而影响耦合波之间的能量转换。我们利用声光耦合波理论研究了基波和倍频波之间的能量转换,通过调节声波的功率密度,可以有效的调节基波和倍频波输出,实现了利用声光效应对超晶格中频率转换的控制。更多还原

【Abstract】 In the past decades, with the development of the quasi-phase matching technology, the solid state lasers, which are made up of optical superlattice, has been made great progress. The advantage of the solid state laser is that it can be made compact, high power and good stability. The LiNbO3 and LiTaO3, with which the optical frequency conversion is easy realized, are widely used by more and more researchers to construct varies of solid state laser. Optical superlattice has been extensively studied for efficient frequency conversion efficiency. The excellent performances such as high amplification, low threshold, and easiness to realize phase matching make optical superlattice especially useful for solid state lasers. As excellent optical materials, LiNbO3 and LiTaO3 also have outstanding electro-optic effect and acousto-optic effect, which can be used to control and modulate the propagation of light in the optical superlattice. In this thesis, we studied experimentally the influence of electro-optic effect on the generation of second harmonic in periodic and quasiperiodic optical superlattice, the electro-optic modulation on coupled quasi-phase matched frequency conversion process. We studied theoretically the modulation of acousto-optic effect on the generation of second harmonic in periodic optical superlattice. The main results are as follows:1. We designed the periodic LN and quasi-periodic LT optical superlattice and realized the modulation of the output of second harmonic generation of 1064nm light. The amplitude and polarization of 532nm were tuned by using the external DC electric field along the Y axis of the sample. 2. We designed the periodic LT optical superlattice for third harmonic generation. With Nd:YVO4 as the laser crystal and an 808nm diode laser as the pump source, the coupled quasi-phase matched frequency conversion was realized. The modulation of the third harmonic in the coupled quasi-phase matched frequency conversion of 1342nm could be modulated by applying an external electric field along the Z axis of the sample.3. We studied theoretically the effect of acousto-optic modulation on quasi-phase matched frequency conversion. An acoustic wave is introduced to modulate the second harmonic generation in an optical superlattice. The wave-coupling equations governing acousto-optic (AO) polarization coupling and frequency doubling in periodically poled lithium niobate are proposed and analyzed. The numerical simulation results show that there is a competition between the AO polarization modulation and second harmonic generation (SHG). The output of second harmonic can be switched or manipulated by the longitudinal acoustic-wave.更多还原