SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK.
Nat Commun. 2013;4:2665. doi: 10.1038/ncomms3665.
Controlling the flux of photons is crucial in many areas of science and technology. Artificial materials with nano-scale modulation of the refractive index, such as photonic crystals, are able to exercise such control and have opened exciting new possibilities for light manipulation. An interesting alternative to such periodic structures is the class of materials known as quasi-crystals, which offer unique advantages such as richer Fourier spectra. Here we introduce a novel approach for designing such richer Fourier spectra, by using a periodic structure that allows us to control its Fourier components almost at will. Our approach is based on binary gratings, which makes the structures easy to replicate and to tailor towards specific applications. As an example, we show how these structures can be employed to achieve highly efficient broad-band light trapping in thin films that approach the theoretical (Lambertian) limit, a problem of crucial importance for photovoltaics.
控制光子的通量在许多科学和技术领域都至关重要。具有纳米级折射率调制的人工材料，如光子晶体，能够进行这种控制，并为光的操控开辟了令人兴奋的新可能性。周期性结构的一种有趣替代品是准晶体类材料，它们具有更丰富的傅里叶谱等独特优势。在这里，我们通过使用一种允许我们几乎随意控制其傅里叶分量的周期性结构，引入了一种设计这种更丰富傅里叶谱的新方法。我们的方法基于二元光栅，这使得结构易于复制，并针对特定应用进行定制。例如，我们展示了这些结构如何能够用于在薄膜中实现高效的宽带光捕获，接近理论（朗伯）极限，这对于光伏来说是一个至关重要的问题。
