从光子晶体效应到表面等离子波的实时演变

Real-time transition of a photonic crystal effect to a surface plasmon resonance

文章报道了激光诱导太赫兹表面等离子谐振效应。采用激光抽运-太赫兹波探测技术,实时改变单晶硅中的载流子浓度,使其介电特性从类绝缘体演变为类金属导体,以支持表面等离子谐振效应,进而实现太赫兹波在周期性亚波长单晶硅孔阵列中的实时可控制谐振增强传输。同时还通过实验观测到太赫兹波从光子晶体效应到表面等离子波的实时演变。文章作者采用Fano模型对实验结果进行模拟分析,获得了与实验数据一致的理论拟合。

We report the experimental observation of light induced terahertz surface plasmons. By use of an optical pump-terahertz probe technique, an instantaneous transition is induced between two interesting optical phenomena, an out-of-plane photonic crystal effect and surface-plasmon resonance, in a thin silicon film perforated with an array of subwavelength holes. The dielectric function of silicon is essentially altered by the intense uhrafast laser pulses due to photo-generated free carriers, whereby the silicon array becomes metallic and favors the coupling and propagation of surface plasmons in the terahertz regime. The plasmonic resonances are well fitted by the Fano model.