共轴环光子晶体的缺陷微腔特性

 采用数值计算方法,模拟了共轴环光子晶体缺陷微腔的谐振模式场分布,计算了此微腔的品质因数和功率损耗,并分析其几何参数对谐振特性的影响。以此缺陷微腔为基础构建周期性慢波系统,讨论了该系统的色散特性。结果表明,微腔中能够存在单一的谐振模式,微腔的纵向长度和介质环介电常数对谐振特性影响较大。所构建的慢波系统有较宽的慢波频域,且慢波比曲线较为平坦。增大电子注开孔半径和减小周期长度对于提高工作频率及增加带宽较为有效。     

Spin Accumulation in a Double Quantum Dot Aharonov-Bohm Interferometer

We investigate the spin accumulation in a double quantum dot Aharonov-Bohm （AB） interferometer in which both the Rashba spin-orbit （RSO） interaction and intradot Coulomb interaction are taken into account. Due to the existence of the RSO interaction, the electron, flowing through different arms of the AB ring, will acquire a spin-dependent phase factor in the tunnel-coupling strengths. This phase factor will induce various interesting interference phenomena. It is found that the electrons of the different spin directions can accumulate in the two dots by properly adjusting the bias and the intradot level with a fixed RSO interaction strength. Moreover, both the magnitude and direction of the spin accumulation in each dot can be conveniently controlled and tuned by the gate voltage acting on the dot or the bias on the lead.