优化光子晶体量子阱透射能带结构的方法

利用传输矩阵法理论,通过数值计算、模拟的方式,研究优化光子晶体量子阱透射能带结构的方法,结果表明：适当调整光子晶体的周期排列结构时,可拓宽光量子阱阱层光子晶体的能带,即可扩大光量子阱透射谱分布的频率范围;当组成光子晶体介质由双正材料置换成双负材料时,光量子阱阱层光子晶体的多能带结构合并成很宽且完整的单能带结构,即可使光量子阱透射谱实现连续频率分布的多通道滤波功能.光子晶体排列结构和不同介质对光量子阱透射能带结构的优化效果不同,对光子晶体量子阱的理论研究、实际设计和应用等,均有积极的指导作用.     

光子晶体滤波器的滤波品质调制因素研究

利用传输矩阵法理论,通过数值计算模拟的方法,研究各种结构参数对光子晶体滤波器滤波品质的调制机制,结果表明:对于双正介质光子晶体,当光子晶体或光子晶体量子阱的排列周期数越大,或基元介质高折射率介质的折射率越大,光子晶体滤波器的滤波品质越高;对于单负介质光子晶体,当光子晶体介质层厚度越大,光子晶体滤波器滤波品质也越高;当双正介质光子晶体的介质换成双负介质时,光子晶体滤波器的滤波品质会降低,但随着双负介质折射率的负值增加,滤波品质会上升。光子晶体或光子晶体量子阱结构参数对滤波器品质的调制机制,为设计光子晶体滤波器以及形成其有效调制机制提供理论参考。     

周期数对光量子阱透射谱的影响

用传输矩阵法理论,研究周期数对一维光子晶体量子阱透射谱的影响,结果表明:随着阱层或垒层周期数的增大,光子晶体量子阱的透射峰均变窄,且垒层周期数增大时透射峰变窄的速度快;垒层介质高低折射率比值越大,或垒层周期数增大,光子晶体量子阱的透射峰变窄速度越快。这些特性,对提高光子晶体光学滤波器件的品质有指导意义。     

双正、双负和单负介质光子晶体能带的比较研究

利用传输矩阵法理论,对双正、双负和单负介质构成的对称结构光子晶体能带谱进行了对比研究,结果得到：由不同介质材料构成的对称结构光子晶体,其能带谱存在很大的差异,其中以单负介质光子晶体禁带宽度最宽,双负介质光子晶体次之,双正介质光子晶体的禁带宽度为最窄;当周期数变大时,光子晶体禁带中的透射峰带宽均逐渐变小并趋于尖锐,且以单负介质的光子晶体透射峰带宽减小的速度为最快;介质厚度dB对单负介质光子晶体的调制效果要优于对双正和双负光子晶体的调制效果;入射角对单负介质光子晶体能带谱的影响要大于对双正和双负介质光子晶体.不同介质材料构成的对称结构光子晶体的这些光传输特性,可为镜像对称结构光子晶体的设计以及窄带或是宽带光子晶体光学滤波器件等提供理论指导.     

磁场作用下超晶格单量子阱中束缚态的能级

超晶格由两种不同晶体材料交替生长的具有周期性结构的多层薄膜构成,两种材料的"势垒—势阱"结构就是量子阱.通过理想的无限深势阱模型,讨论了施加磁场作用的超晶格中单量子阱束缚态的能级结构和态密度,得到了体系的本征能量与本征函数.分析表明,沿超晶格生长方向能级不受外加磁场影响,垂直于超晶格生长方向以ωc为回旋频率的谐振运动,超晶格量子阱量子化能级高度简并,简并度和外加磁场成正比.     

Ge/Ge_(0.85)Si_(0.15)量子阱发光结构设计

提出了采用Ge/Ge_(0.85)Si_(0.15)量子阱结构制备Ge材料直接带隙发光器件的设计方法。基于量子力学理论,设计得到不同量子阱宽度下的能级分布情况以及载流子在Γ1-HH1之间的复合随量子阱宽度的变化趋势。设计结果给出了具体的能级与波函数的分布情况,可为实验制备Ge/Ge_(0.85)Si_(0.15)量子阱发光器件提供理论指导。     

非对称量子阱中非线性三次谐波特性研究

主要研究了一个特殊非对称量子阱中的三次谐波。首先利用量子力学中的密度矩阵算符理论和迭代方法导出了量子阱中的三次谐波表达式，然后以典型的非对称量子阱材料为例作了数值计算。数值结果表明，入射光强以及系统的非对称性对三次谐波的改变有较大影响，从而为实验研究提供理论依据。     

980nm激光器有源区的设计与分析

有源区设计是半导体激光器设计的核心部分,其材料、参数的选择将直接决定激光器的最终属性,而有源区设计的关键之处在于其能带结构分析。利用四带模型和固体模型理论可研究量子阱有源区的价带色散关系,进而推算出增益谱、透明载流子浓度等重要参数。本文针对GaAs基980nm激光器有源区的InGaAs／GaAsP应变补偿量子阱和InCaAs／GaAs普通应变量子阱结构进行理论分析比较。分析结果表明,应变补偿量子阱具有带阶大,峰值增益高,波长漂移速度更低和透明载流子浓度更低等优势,这意味着采用该有源区结构的激光器将有更优越的光电性质。     

Rashba多量子阱异质结中自旋轨道耦合效应对电子输运的影响

根据量子相干输运理论,利用传递矩阵的方法,研究自旋电子在铁磁体（F）／半导体多量子阱（SWM）／铁磁体的一维结构中,考虑自旋轨道耦合效应时的量子相干输运的特性．通过计算发现在这种一维多量子阱结构中的自旋电子的输运特性发生了一定的变化．这有利于进一步提高自旋电子的隧穿系数和自旋极化率．     

用概率迭加方法处理七重势垒散射问题

根据量子力学路径积分的基本思想，研究了七重势垒量子阱结构的散射问题，严格导出了势垒的反射系数和透射系数表达式，由此可以得到共振隧道条件的解析关系式，给出了研究多重势垒量子阱结构隧道效应的一种新的理论方法。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…