Tang Lei, Francoeur Mathieu
Opt Express. 2017 Nov 27;25(24):A1043-A1052. doi: 10.1364/OE.25.0A1043.
A novel photonic thermal diode concept operating in the near field and capitalizing on the temperature-dependence of coupled surface polariton modes in nanostructures is proposed. The diode concept utilizes terminals made of the same material supporting surface polariton modes in the infrared, but with dissimilar structures. The specific diode design analyzed in this work involves a thin film and a bulk, both made of 3C silicon carbide, separated by a subwavelength vacuum gap. High rectification efficiency is obtained by tuning the antisymmetric resonant modes of the thin film, resulting from surface phonon-polariton coupling, on- and off-resonance with the resonant mode of the bulk as a function of the temperature bias direction. Rectification efficiency is investigated by varying structural parameters, namely the vacuum gap size, the dielectric function of the substrate onto which the film is coated, and the film thickness to gap size ratio. Calculations based on fluctuational electrodynamics reveal that high rectification efficiencies in the 80% to 87% range can be maintained in a wide temperature band (~700 K to 1000 K). The rectification efficiency of the proposed diode concept can potentially be further enhanced by investigating more complex nanostructures such as gratings and multilayered media.
提出了一种新型的光子热二极管概念，其在近场中工作，并利用纳米结构中耦合表面极化子模式的温度依赖性。该二极管概念采用由相同材料制成的终端，这些终端在红外波段支持表面极化子模式，但结构不同。在这项工作中分析的特定二极管设计涉及一个薄膜和一个块体，二者均由3C碳化硅制成，中间隔着一个亚波长真空间隙。通过调节薄膜的反对称共振模式（由表面声子 - 极化子耦合产生）与块体的共振模式在温度偏置方向作用下的共振和非共振状态，可获得高整流效率。通过改变结构参数，即真空间隙尺寸、涂覆薄膜的衬底的介电函数以及薄膜厚度与间隙尺寸之比，来研究整流效率。基于波动电动力学的计算表明，在宽温度范围（约700 K至1000 K）内，可保持80%至87%范围内的高整流效率。通过研究更复杂的纳米结构，如光栅和多层介质，所提出的二极管概念的整流效率可能会进一步提高。
