Abstract Semiconductor superlattices are strongly nonlinear media offering several technological challenges associated with the generation of high-frequency Gigahertz radiation and very effective frequency multiplication up to several Terahertzs. However, charge accumulation, traps and interface defects lead to pronounced asymmetries in the nonlinear current flow, from which high harmonic generation stems. This problem requires a full non-perturbative solution of asymmetric current flow under irradiation, which we deliver in this paper within the Boltzmann-Bloch approach. We investigate the nonlinear output on both frequency and time domains and demonstrate a significant enhancement of even harmonics by tuning the interface quality. Moreover, we find that increasing arbitrarily the input power is not a solution for high nonlinear output, in contrast with materials described by conventional susceptibilities. There is a complex combination of asymmetry and power values leading to maximum high harmonic generation.

中文翻译：

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谐波乘法器中千兆赫-太赫兹生成的超晶格非线性

摘要 半导体超晶格是强非线性介质，在产生高频千兆赫辐射和高达数太赫兹的非常有效的倍频方面存在多项技术挑战。然而，电荷积累、陷阱和界面缺陷导致非线性电流的明显不对称，由此产生高次谐波。这个问题需要辐照下不对称电流的完整非微扰解，我们在本文中使用 Boltzmann-Bloch 方法提供。我们研究了频域和时域上的非线性输出，并通过调整接口质量证明了偶次谐波的显着增强。此外，我们发现任意增加输入功率不是高非线性输出的解决方案，与常规磁化率描述的材料相反。不对称性和功率值的复杂组合导致产生最大的高次谐波。