Large optical nonlinearity enabled by coupled metallic quantum wells
Large optical nonlinearity enabled by coupled metallic quantum wells
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DOI：
10.1038/s41377-019-0123-4
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发表时间：
2019-01-23
影响因子：
19.4
通讯作者：
Liu, Zhaowei
中科院分区：
文献类型：
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作者：
Qian, Haoliang;Li, Shilong;Liu, Zhaowei
在所需工作频率下表现出强二阶光学非线性的新材料对于非线性光学是至关重要的。在半导体量子威尔斯（QW）中获得了巨二阶极化率χ（2）。不幸的是，在半导体量子阱中的有限的限制潜力导致了巨大的挑战，在缩放这样的计划，以更重要的非线性光学应用的可见/近红外（NIR）频率。在这里，我们介绍一种金属/电介质异质结构平台，即，TiN/Al 2 O3外延多层膜，以克服这一限制。该平台在NIR频率下具有约1500 pm/V的极高chi（（2））。通过将上述异质结构与由纳米结构超颖表面提供的大电场增强相结合，二次谐波产生（SHG）的功率效率在10 GW/cm（2）的入射脉冲强度下达到10（-4），这与在类似频率下来自非线性表面的先前演示相比是几个数量级的改进。所提出的量子工程异质结构能够在可见光/NIR频率下有效地将波混频成超紧凑的非线性光学器件。
New materials that exhibit strong second-order optical nonlinearities at a desired operational frequency are of paramount importance for nonlinear optics. Giant second-order susceptibility chi((2)) has been obtained in semiconductor quantum wells (QWs). Unfortunately, the limited confining potential in semiconductor QWs causes formidable challenges in scaling such a scheme to the visible/near-infrared (NIR) frequencies for more vital nonlinear-optic applications. Here, we introduce a metal/dielectric heterostructured platform, i.e., TiN/Al2O3 epitaxial multilayers, to overcome that limitation. This platform has an extremely high chi((2)) of approximately 1500 pm/V at NIR frequencies. By combining the aforementioned heterostructure with the large electric field enhancement afforded by a nanostructured metasurface, the power efficiency of second harmonic generation (SHG) achieved 10(-4) at an incident pulse intensity of 10 GW/cm(2), which is an improvement of several orders of magnitude compared to that of previous demonstrations from nonlinear surfaces at similar frequencies. The proposed quantum-engineered heterostructures enable efficient wave mixing at visible/NIR frequencies into ultracompact nonlinear optical devices.