Nazarova Dimana, Nedelchev Lian, Berberova-Buhova Nataliya, Mateev Georgi
Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
Department of Physics, University of Chemical Technology and Metallurgy, 1756 Sofia, Bulgaria.
Nanomaterials (Basel). 2023 Nov 14;13(22):2946. doi: 10.3390/nano13222946.
Photoanisotropic materials, in particular azodyes and azopolymers, have attracted significant research interest in the last decades. This is due to their applications in polarization holography and 4G optics, enabling polarization-selective diffractive optical elements with unique properties, including circular polarization beam-splitters, polarization-selective bifocal lenses, and many others. Numerous methods have been applied to increase the photoinduced birefringence of these materials, and as a result, to obtain polarization holographic elements with a high diffraction efficiency. Recently, a new approach has emerged that has been extensively studied by many research groups, namely doping azobenzene-containing materials with nanoparticles with various compositions, sizes, and morphologies. The resulting nanocomposites have shown significant enhancement in their photoanisotropic response, including increased photoinduced birefringence, leading to a higher diffraction efficiency and a larger surface relief modulation in the case of polarization holographic recordings. This review aims to cover the most important achievements in this new but fast-growing field of research and to present an extensive comparative analysis of the result, reported by many research groups during the last two decades. Different hypotheses to explain the mechanism of photoanisotropy enhancement in these nanocomposites are also discussed. Finally, we present our vision for the future development of this scientific field and outline its potential applications in advanced photonics technologies.
光各向异性材料，特别是偶氮染料和偶氮聚合物，在过去几十年中引起了广泛的研究兴趣。这是由于它们在偏振全息术和4G光学中的应用，能够制造出具有独特性能的偏振选择性衍射光学元件，包括圆偏振分束器、偏振选择性双焦点透镜等等。人们已经应用了许多方法来提高这些材料的光致双折射，从而获得具有高衍射效率的偏振全息元件。最近，出现了一种新方法，许多研究小组对其进行了广泛研究，即使用具有不同组成、尺寸和形态的纳米颗粒对含偶氮苯的材料进行掺杂。所得的纳米复合材料在光各向异性响应方面有显著增强，包括光致双折射增加，这在偏振全息记录中导致更高的衍射效率和更大的表面起伏调制。本综述旨在涵盖这一新兴但快速发展的研究领域的最重要成果，并对许多研究小组在过去二十年中报告的结果进行广泛的比较分析。还讨论了解释这些纳米复合材料中光各向异性增强机制的不同假设。最后，我们阐述了对这一科学领域未来发展的展望，并概述了其在先进光子技术中的潜在应用。
