Goessling Johannes W, Wardley William P, Lopez-Garcia Martin
International Iberian Nanotechnology Laboratory Braga 4715-330 Portugal.
Adv Sci (Weinh). 2020 Mar 21;7(10):1903726. doi: 10.1002/advs.201903726. eCollection 2020 May.
Slab photonic crystals (PhCs) are photonic structures used in many modern optical technologies. Fabrication of these components is costly and usually involves eco-unfriendly methods, requiring modern nanofabrication techniques and cleanroom facilities. This work describes that diatom microalgae evolved elaborate and highly reproducible slab PhCs in the girdle, a part of their silicon dioxide exoskeletons. Under natural conditions in water, the girdle of the centric diatom shows a well-defined optical pseudogap for modes in the near-infrared (NIR). This pseudogap shows dispersion toward the visible spectral range when light is incident at larger angles, eventually facilitating in-plane propagation for modes in the green spectral range. The optical features can be modulated with refractive index contrast. The unit cell period, a critical factor controlling the pseudogap, is highly preserved within individuals of a long-term cultivated inbred line and between at least four different cell culture strains tested in this study. Other diatoms present similar unit cell morphologies with various periods. Diatoms thereby offer a wide range of PhC structures, reproducible and equipped with well-defined properties, possibly covering the entire UV-vis-NIR spectral range. Diatoms therefore offer an alternative as cost-effective and environmentally friendly produced photonic materials.
平板光子晶体（PhCs）是许多现代光学技术中使用的光子结构。这些组件的制造成本高昂，通常涉及不环保的方法，需要现代纳米制造技术和洁净室设施。这项工作描述了硅藻微藻在其二氧化硅外骨骼的一部分——环带中进化出了精细且高度可重复的平板光子晶体。在水中的自然条件下，中心硅藻的环带对近红外（NIR）模式显示出明确的光学赝隙。当光以较大角度入射时，该赝隙向可见光谱范围色散，最终促进绿色光谱范围内模式的面内传播。光学特征可以通过折射率对比度进行调制。晶胞周期是控制赝隙的关键因素，在长期培养的自交系个体内以及本研究中测试的至少四种不同细胞培养菌株之间高度保持一致。其他硅藻呈现出具有不同周期的类似晶胞形态。因此，硅藻提供了广泛的光子晶体结构，可重复且具有明确的特性，可能覆盖整个紫外 - 可见 - 近红外光谱范围。因此，硅藻作为具有成本效益且环保生产的光子材料提供了一种替代方案。
