Light Emission near a Gradient Metasurface

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• 作者：Leonard C. Kogos ; Roberto Paiella
• 刊名：ACS Photonics
• 出版年：2016
• 出版时间：February 17, 2016
• 年：2016
• 卷：3
• 期：2
• 页码：243-248
• 全文大小：531K
• ISSN：2330-4022

文摘

Gradient metasurfaces have recently emerged as a powerful tool for the control of externally incident optical wavefronts. Here we present a theoretical study showing how they can also dramatically modify the radiation properties of light emitters located in their near-field zone. First, the spontaneous emission decay of a dipole source can be greatly accelerated through near-field interactions involving evanescent waves at the metasurface, by an amount that depends on the dipole lateral position in an oscillatory fashion. Second, as a result of these interactions, highly asymmetric directional radiation patterns can be produced in the far field, with broad geometrical tunability of the angle of peak emission. Furthermore, the total output radiation power can be increased in the case of low-efficiency emitters or quenched in favor of directional excitation of surface waves depending on the metasurface phase gradient. These phenomena could not be explained simply in terms of anomalous reflection of externally incident dipole radiation by the metasurface, but rather are a direct consequence of a distinctive coupling between a wide range of evanescent and propagating waves enabled by these nanostructures. The resulting ability to control the output of radiation processes directly at the source level (without any external optics) is attractive for future applications in highly miniaturized optical systems.