Strong Enhancement of Second Harmonic Emission by Plasmonic Resonances at the Second Harmonic Wavelength
Strong Enhancement of Second Harmonic Emission by Plasmonic Resonances at the Second Harmonic Wavelength
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DOI：
10.1021/acs.nanolett.5b00747
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发表时间：
2015-06-01
期刊：
影响因子：
10.8
通讯作者：
Giessen, Harald
中科院分区：
文献类型：
--
作者：
Metzger, Bernd;Gui, Lili;Giessen, Harald
我们进行二次谐波光谱的铝纳米天线阵列，表现出等离子体共振在第二谐波波长450和570 nm之间的聚焦子30 fs的激光脉冲可调从900到1140 nm的纳米天线阵列上。我们发现，在第二谐波波长的等离子体激元共振提高了超过一个数量级的整体非线性过程。特别地，在测量中，当与垂直的非谐振第二谐波偏振相比时，谐振第二谐波偏振分量是大约70的因子。此外，二次谐波转换效率的最大值被发现是轻微的蓝移相对于线性光学远场光谱的峰值。这一事实可以从一个简单的模型来理解，该模型解释了在基波波长处的几乎非共振吸收和在二次谐波处的共振发射过程。
We perform second harmonic spectroscopy of aluminum nanoantenna arrays that exhibit plasmonic resonances at the second harmonic wavelength between 450 and 570 nm by focusing sub-30 fs laser pulses tunable from 900 to 1140 nm onto the nanoantenna arrays. We find that a plasmonic resonance at the second harmonic wavelength boosts the overall nonlinear process by more than an order of magnitude. In particular, in the measurement the resonant second harmonic polarization component is a factor of about 70 stronger when compared to the perpendicular off-resonant second harmonic polarization. Furthermore, the maximum of the second harmonic conversion efficiency is found to be slightly blue-shifted with respect to the peak of the linear optical far-field spectrum. This fact can be understood from a simple model that accounts for the almost off-resonant absorption at the fundamental wavelength and the resonant emission process at the second harmonic.