Simulation of Electric Quadrupole and Magnetic Dipole Transition Efficiencies in Optical Near Fields Generated by a Subwavelength Slit Array(Atomic and molecular physics)
Simulation of Electric Quadrupole and Magnetic Dipole Transition Efficiencies in Optical Near Fields Generated by a Subwavelength Slit Array(Atomic and molecular physics)
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DOI：
10.1143/jpsj.78.024301
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发表时间：
2009-01
影响因子：
1.7
通讯作者：
K. Deguchi;M. Okuda;A. Iwamae;Hiroaki Nakamura;K. Sawada;M. Hasuo
中科院分区：
文献类型：
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作者：
K. Deguchi;M. Okuda;A. Iwamae;Hiroaki Nakamura;K. Sawada;M. Hasuo
我们用时域有限差分法计算了由50 nm厚的金膜组成的周期性结构的50 nm宽狭缝阵列产生的光学近场。电四极（E2）和磁偶极子（M1）的过渡，这是与激发光场的空间导数的影响，计算的光场进行评估。在入射光的偏振垂直于狭缝方向的情况下，E2跃迁效率大大提高，而对于该偏振的M1跃迁，不期望这样的提高。E2跃迁效率的大幅度提高不仅源于场的增强，而且源于场在狭缝边缘附近的局部化。E2跃迁效率的增强的狭缝周期依赖性表明增强受表面等离子体共振的影响。当入射光的偏振方向平行于狭缝时，得到了小的增强。
We calculate optical near fields generated by a periodically structured 50-nm-wide slit array of a 50-nm-thick gold film with a finite difference time domain method. Efficiencies of the electric quadrupole (E2) and magnetic dipole (M1) transitions, which are associated with the space derivative of the excitation light field, are evaluated for the calculated optical fields. The E2 transition efficiency is largely enhanced in the case where the polarization of the incident light is perpendicular to the slit direction, while such an enhancement is not expected for the M1 transition for this polarization. The large enhancement of the E2 transition efficiency originates not only from the field enhancement but also from its localization near the slit edge. The slit period dependence of the enhancement of the E2 transition efficiency suggests the enhancement to be affected by surface plasmon resonance. In the case where the polarization of the incident light is parallel to the slit, a small enhancement is obtain...