超短脉冲激光在DBASVP分子中传播时的双光子面积演化和光限幅效应  

Two-photon area evolution and optical limiting of ultrashort laser pulses in DBASVP molecule media

作　　者：苗泉[1] 赵鹏[1] 孙玉萍[1] 刘纪彩[1] 王传奎[1] 

机构地区：[1]山东师范大学物理与电子科学学院,济南250014

出　　处：《物理学报》2009年第8期5455-5461,共7页Acta Physica Sinica

基　　金：国家重点基础研究发展计划(批准号:2006CB806000);山东省自然科学基金(批准号:Z2007A02)资助的课题~~

摘　　要：以一维不对称π共轭分子体系(DBASVP分子)为介质,在双光子共振条件下,从双光子面积定理和严格数值求解Maxwell-Bloch方程两方面出发,分别研究超短脉冲激光在该有机分子介质中的传播过程,从而探讨双光子面积的演化规律,并分析双光子面积定理的适用性.提出了一种数值模拟分子介质光限幅特性的理论方法.分子的电子结构和电偶极矩是基于密度泛函理论利用从头计算方法得到的.研究结果表明,基于慢变幅和慢变相近似以及单模场条件下的双光子面积定理不能很好地描述超短脉冲的双光子面积在该分子介质中的演化规律.基于双光子吸收的分子光限幅特性与分子介质的厚度有关.Taking the one-dimensional asymmetrical π conjugation molecule material （DBASVP molecules） as medium, with the two- photon resonance, we studied the propagation of ultrashort laser pulses in the medium based on the two-photon area theorem and the numerical solutions of the coupled Bloch and Maxwell＇ s equations. The evolution of two-photon area is thus investigated and the applicability of the two-photon area is then discussed. A theoretical method for simulating the optical limiting properties of molecular medium is pointed out. The molecular electronic structures and dipole moments are calculated by use of density functional theory at ab initio level. The numerical results show that the two-photon area theorem based on the slowly varying envelope and phase approximations cannot accurately describe the evolvution of the two-photon area in the molecular medium. The optical limiting behavior based on the two-photon absorption is related to the width of the molecular medium.

关 键 词：双光子吸收 光限幅效应 双光子面积定理 超短脉冲激光 

分 类 号：O437[机械工程—光学工程] TN241[理学—光学]