Kujala Sami, Canfield Brian K, Kauranen Martti, Svirko Yuri, Turunen Jari
Optics Laboratory, Institute of Physics, Tampere University of Technology, PO Box 692, FI-33101 Tampere, Finland.
Phys Rev Lett. 2007 Apr 20;98(16):167403. doi: 10.1103/PhysRevLett.98.167403. Epub 2007 Apr 18.
We provide experimental evidence of higher multipole (magnetic dipole and electric quadrupole) radiation in second-harmonic (SH) generation from arrays of metal nanoparticles. Fundamental differences in the radiative properties of electric dipoles and higher multipoles yield opposite interference effects observed in the SH intensities measured in the reflected and transmitted directions. These interference effects clearly depend on the polarization of the fundamental field, directly indicating the importance of multipole effects in the nonlinear response. We estimate that higher multipoles contribute up to 20% of the total emitted SH field amplitude for certain polarization configurations.
我们提供了实验证据，证明金属纳米颗粒阵列在二次谐波（SH）产生过程中存在更高阶的多极（磁偶极和电四极）辐射。电偶极和更高阶多极辐射特性的根本差异，在反射和透射方向测量的SH强度中产生了相反的干涉效应。这些干涉效应明显取决于基频场的极化，直接表明了多极效应在非线性响应中的重要性。我们估计，对于某些极化配置，更高阶多极对总发射SH场振幅的贡献高达20%。
