双波泵浦量子阱子带共振跃迁的非线性光学性质  

Nonlinear optical effects in asymmetric quantum well based on resonant subband transitions

作　　者：曹小龙[1,2,3] 车永莉[2,3] 姚建铨[2,3] 

机构地区：[1]山东科技大学机械电子工程学院,山东青岛266590 [2]天津大学精密仪器与光电子工程学院,天津300072 [3]光电信息技术教育部重点实验室(天津大学),天津300072

出　　处：《红外与毫米波学报》2016年第4期442-448,共7页Journal of Infrared and Millimeter Waves

基　　金：国家自然科学基金(61271066);山东科技大学人才引进科研启动基金(2014RCJJ020)~~

摘　　要：设计了组分为Al_(0.5)Ga_(0.5)As/GaAs/Al_(0.2)Ga_(0.8)As阶梯形量子阱结构,其导带子带能级可与中红外双波长CO_2激光器的泵浦光光子能量共振.计算了此量子阱对两束泵浦光的二阶非线性差频系数χ_(DFG)^((2))及三阶非线性系数χ_(ω1)^((3))和χ_(ω2)^((3))的表达式;在导带分别为抛物线形和非抛物线形两种条件下,对比研究了三个非线性系数随两束泵浦光波长的变化.χ_(DFG)^((2))、χ_(ω1)^((3))和χ_(ω2)^((3))随两束泵浦光波长λ_(p1)和λ_(p2),都是呈现出先增大后减小的变化趋势,对应不同泵浦波长,存在一个峰值;相比于导带为抛物线形,在非抛物线条件下三个非线性系数随短波长的泵浦光λ_(p1)的变化出现"红移"现象,而随长波长的泵浦光λ_(p2)的变化峰值位置基本相同;由量子限制效应导致的两种导带情况下子带能级变化,即与泵浦光光子共振条件发生变化,是出现"红移"的原因;而峰值数值上的差异,主要由量子阱子带能级间的跃迁矩阵元和两种导带条件下不同的能级差决定.Based on resonant subband transitions, the second-order and third-order nonlinear optical effects in an asymmetric quantum well （AQW） with the structure of GaAs/Al0.2Ga0.8As/Al0.5Ga0.5As have been theoretically investigated on the conditions of parabolic and non-parabolic bands. With the increase of two pump wavelengths λp1 and λp2 separately, the second-order nonlinear difference frequency susceptibility XDFG（2） and the two third-order nonlinear susceptibilities Xω1^（3） and Xω2（3） increase to a maximum value, and then drops down rapidly. In comparison with the condition of parabolic subband, the curves of XDFG（2）Xω1^（3） and Xω2（3） show obvious red-shift as a function of the short pump wave on the the curves XDFG（2）Xω1^（3） and Xω2（3） condition of nonparabolic subband. However, with the increase of long pump wave λp2, no changes of peak position have been discovered. The physical origin of all red-shift in nonlinear optical effects is the different energy level gaps on the two conditions of subband, which causes the changes in resonant condition. The primary reason for different peak values is the different transition matrix elements, and the other reason is energy level gaps.

关 键 词：非线性光学性质 非对称量子阱 非抛物线形 跃迁矩阵元 

分 类 号：O472.3[理学—半导体物理] O437.1[理学—物理]