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51.
Polarization switching and synchronization of mutually coupled vertical-cavity surface-emitting semiconductor lasers
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Polarization switching (PS) dynamics and synchronization
performances of two mutually coupled vertical-cavity
surface-emitting lasers (VCSELs) are studied theoretically in
this paper. A group of dimensionless rate equations is derived
to describe our model. While analysing the PS characteristics,
we focus on the effects of coupling rate and frequency detuning
regarding different mutual injection types. The results indicate
that the x-mode injection defers the occurrence of PS, while
the y-mode injection leads the PS to occur at a lower current.
Strong enough polarization-selective injection can suppress the
PS. Moreover, if frequency detuning is considered, the effects
of polarization-selective mutual injection will be weakened. To
evaluate the synchronization performance, the correlation
coefficients and output dynamics of VCSELs with both pure mode
and mixed mode polarizations are given. It is found that
performance of complete synchronization is sensitive to the
frequency mismatch but it is little affected by mixed mode
polarizations, which is opposite to the case of
injection-locking synchronization. 相似文献
52.
The properties of the ground state of a closed dot-ring system with a magnetic flux in the Kondo regime are studied theoretically by means of a one-impurity Anderson Hamiltonian. The Hamiltonian is solved by means of the slave-boson mean-field theory. It is shown that at T=0, a suppressed Kondo effect exists in this system even when the mean level spacing of electrons in the ring is larger than the bulk Kondo temperature. The physical quantities depend sensitively on both the parity of the system and the size of the ring; the rich physical behaviour can be attributed to the coexistence of both the finite-size effect and the Kondo screening effect. It is also possible to detect the Kondo screening cloud by measuring the persistent current or the zero field impurity susceptibility χ_{imp} directly in future experiments. 相似文献
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微乳液电动色谱测定油-水分配系数的改进方法研究 总被引:1,自引:0,他引:1
通过考察微乳液电动色谱(MEEKC)中化合物浓度和高电场对其迁移行为的影响, 探讨了化合物分配于微乳后改变微乳内相性质的原因, 以及电泳高电场致使微乳液性质变化的机理. 在此基础上建立了一种测定化合物油-水分配系数的改进型MEEKC方法. 将此改进方法应用于烷基苯化合物之油-水分配系数的测定, 其测定值与文献参考值平均相差0.07个对数单位, 准确度较现行MEEKC方法有了明显提高. 相似文献
58.
0引言直接甲醇燃料电池(DMFC)由于其燃料来源丰富、价格低廉、甲醇携带和储存安全方便等独特的优越性而越来越受到重视[1]。但DMFC中常用的阳极Pt催化剂对甲醇氧化的低的电催化活性及易于被甲醇氧化的中间体,吸附态的CO(COad)毒化的问题一直是制约DMFC走向实用化的关键问题[2,3]。由于甲醇分子小,在质子交换膜上有较大的透过作用,并且甲醇具有较高的毒性,所以寻求甲醇的替代燃料也是一直以来被广泛关注的问题[4,5]。乙醇是最简单的链醇分子,相对于甲醇来说,乙醇有很多优点,乙醇基本上没有毒性,来源丰富,价格可与甲醇竞争,能量密度高… 相似文献
59.
A series of l-(4′-ethylbiphenylyl) 2-(4-alkoxy-2,3,5,6-tetrafluorophenyl)acetylenes and their nonfluorinated analogues have been prepared. The polarizing microscope observation shows that the fluorinated target compounds exhibit enantiotropic nematic phases, whereas the nonfluorinated analogues show complicated DSC results. The effect of structure modification of the core on mesogenic phases was discussed by comparing the data of fluorinated target compounds with those of corresponding nonfluorinated analogues. 相似文献
60.
XU Yu-Lian WANG Wei-Li CHEN Qi WEN Jian-Xun Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai China 《中国化学》1994,12(2):169-173
A homologous series of 4'-methylphenyl 4"-[(4-alkoxy-2,3,5,6-tetrafluorophenyl)ethynyl]-benzoates have been synthesized. Polarizing microscopic textural observation shows that such compounds exhibit enantiotropic nematic phase. 相似文献