Nonlinear Terahertz Metamaterials via Field-Enhanced Carrier Dynamics in GaAs
Nonlinear Terahertz Metamaterials via Field-Enhanced Carrier Dynamics in GaAs
复制标题
DOI：
10.1103/physrevlett.110.217404
复制
发表时间：
2013-05-21
影响因子：
8.6
通讯作者：
Averitt, Richard D.
中科院分区：
文献类型：
--
作者：
Fan, Kebin;Hwang, Harold Y.;Averitt, Richard D.
我们展示了GaAs上的非线性超材料开口环谐振器（SRR）在太赫兹频率。对于掺杂GaAs膜上的SRR，具有类似于20-160 kV/cm的峰值场的入射太赫兹辐射驱动谷间散射。由于掺杂薄膜的电导率降低，这降低了载流子迁移率并增强了SRR LC响应。高于类似于160 kV/cm，SRR间隙内的电场增强导致有效的碰撞电离，增加载流子密度和电导率，这反过来又抑制了SRR谐振。我们证明了高达10个数量级的载流子密度在半绝缘GaAs上的SRR间隙的增加。此外，我们表明，有效的介电常数可以从负值扫描到正值的影响电离制度中的太赫兹场强度的增加，使新的非线性超材料的可能性。
We demonstrate nonlinear metamaterial split ring resonators (SRRs) on GaAs at terahertz frequencies. For SRRs on doped GaAs films, incident terahertz radiation with peak fields of similar to 20-160 kV/cm drives intervalley scattering. This reduces the carrier mobility and enhances the SRR LC response due to a conductivity decrease in the doped thin film. Above similar to 160 kV/cm, electric field enhancement within the SRR gaps leads to efficient impact ionization, increasing the carrier density and the conductivity which, in turn, suppresses the SRR resonance. We demonstrate an increase of up to 10 orders of magnitude in the carrier density in the SRR gaps on semi-insulating GaAs. Furthermore, we show that the effective permittivity can be swept from negative to positive values with an increasing terahertz field strength in the impact ionization regime, enabling new possibilities for nonlinear metamaterials.