We performed numerical simulations of plasmonic near-field enhancement in Si-based structures in near infrared region. Gold films perforated with periodic two-dimensional subwavelength hole arrays were used as the plasmonic couplers. The array periodicity was adjusted to excite the surface plasmon modes at the telecom wavelengths (between 1.3 and 1.55 μm). The field intensity enhancement factor and its spectral position, as a function of hole diameter, demonstrate the maximum at which the Bloch plasmon polariton waves propagating along the Au–Si interface change by a localized surface plasmon mode. The maximum peak wavelength and field intensity enhancement are reached at d/a = 0.5, where d is the hole diameter and a is the array periodicity. An over 14 times field intensity enhancement was obtained at λ = 1.54 μm for d = 200 nm and a = 400 nm. We found that the localized surface plasmon mode is confined mainly under the Au regions along the diagonals of the square lattice of holes. The lateral field distribution for propagating modes has either a hexagonal or square shape, reflecting in-pane symmetry of the grating. For structures with largest holes, the anticrossing of localized mode with the propagating one was observed implying coupling between the modes and formation of a mixed near-field state. The information acquired from the study is valuable for feasible device applications.

我们在近红外区域的硅基结构中进行了等离子体近场增强的数值模拟。穿孔有周期性二维亚波长孔阵列的金膜用作等离子体耦合器。调整阵列周期性以激发在电信波长（1.3和1.55μm之间）的表面等离子体激元模式。场强增强因子及其光谱位置与孔径的关系表明，沿Au-Si界面传播的Bloch等离子体激元极化波通过局部表面等离子体激元模式变化的最大值。在d / a  = 0.5时达到最大峰值波长和场强增强，其中d是孔径和a是数组周期性。 对于d  ＝ 200nm和a  ＝400nm，在λ＝1.54μm处获得超过14倍的场强度增强。我们发现，局部表面等离激元模式主要被限制在沿着孔的方格对角线的金区域内。传播模式的横向场分布具有六边形或正方形形状，反映了光栅的面内对称性。对于具有最大孔的结构，观察到局部模式与正在传播的模式的反交叉，这暗示了模式之间的耦合以及混合近场状态的形成。从研究中获得的信息对于可行的设备应用是有价值的。