基于超表面材料的光波相位精密操控新技术

Accurate controlling of optical phase based on metasurfaces

  • 摘要: 近年来,基于超表面材料的研究发现了很多新的光学现象,其中几何相位调制是最具吸引力的方向之一。笔者介绍了超表面材料用于光波相位精密操控方面的研究,包括电磁响应的各向异性、电磁共振等机理研究、以及一系列新概念光器件。研究表明,基于金纳米棒超表面材料制造的计算全息片,能够在波长为630 nm~1 050 nm的宽带范围内高效工作,且在波长825 nm处的衍射效率超过80%;基于硅材料超表面材料制造的光分束器,能够在远场形成衍射角为59°×59°的4×4个均匀点阵,且其衍射效率在波长为1 530 nm~1 565 nm的范围内超过50%;基于硅材料超表面材料制造的偏振分离器,其在纳米棒长轴方向的反射率高达98.5%,在短轴方向透过率达到94.7%,且仅需通过调节纳米棒的宽度,就可以在波长为1 460 nm~1 625 nm的宽带范围内任意选择峰值反射波长。研究结果表明,基于几何相位调制机理的超表面材料在具备连续、任意、精密、高效的相位操控等优点的同时,在制造上却仅需要简单的二台阶微纳光学工艺条件,可用于打造新一代高性能、芯片级的光电子元器件,在光纤通信、军事国防、工业及消费电子等领域得到重要应用。

     

    Abstract: In recent years, a lot of new optical phenomena have been discovered based on research of metasurfaces. Among them, geometric phase modulation is one of the most attractive directions. In this paper, some innovation research works in our group on accurate controlling of optical phase based on metasurfaces have been introduced, including anisotropy in electromagnetic response and electromagnetic resonances. Based on these principles, a series of new-concept optical elements and devices have been proposed and investigated. Firstly, a gold nanorod-based CGH (Computer Generated Hologram) was realized. Experimental results show that it can work in broad bandwidth of 630 nm~1 050 nm and the maximum diffraction efficiency reaches 80% at a wavelength of 825 nm. Secondly, a silicon nanorod beam splitter was proposed and it can generate uniform 4 × 4 spot arrays with an extending angle of 59° × 59° in far field. For such device, diffraction efficiency exceeds 50% in ranges of 1530 nm~1 565 nm. At last, a polarising beam splitter was designed with reflectivity of 98.5% along long axis of nanorod, whilst transmissivity along short axis is 94.3%. More interesting, only by changing width of nanorod, we can shift peak response wavelength from 1 460 nm to 1 625 nm. Above research results show that, with advantages such as single-step nanofabrication, continuous, arbitrary, accurate and efficient phase controlling, metasurfaces have brilliant commercial prospects. We predict that metasurfaces will be applied to develop new generation of chip-scale optoelectronic components and devices with high performance. Its application fields can cover optical telecommunication, military defense, industry and consumer electronics.

     

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