Kobayashi Yoichi, Abe Jiro
Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
Department of Chemistry, School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan.
Chem Soc Rev. 2022 Apr 4;51(7):2397-2415. doi: 10.1039/d1cs01144h.
Incoherent nonlinear photophysical and photochemical processes based on stepwise two-photon absorption (2PA) processes have been recently used in materials science owing to their unique photoresponses beyond one-photon processes and lower power thresholds to induce the processes than those of coherent nonlinear optical processes. Among them, nonlinear photochromic materials have received considerable attention because they exhibit unconventional photoresponses compared with other incoherent nonlinear processes such as low-power-threshold nonlinear photoresponses with unimolecular systems, gated photochemical reactions and oxygen-insensitive nonlinear photoresponses. Nonlinear photochromic materials are important not only for colorimetric materials, but also for emergent materials that can enrich the next-generation society such as dynamic holographic materials, which are promising for three-dimensional displays. In this tutorial review, we introduce low-power-threshold nonlinear photochromic materials using stepwise 2PA processes. First, we explain the fundamental concepts of photochemistry as well as photochromic reactions. We attempt to provide an intuitive understanding of incoherent nonlinear optical processes using these fundamental concepts. Then, we introduce several recent examples and potential applications of nonlinear photochromic materials. This tutorial review is important for understanding the scientific progress related to these fields and provides a simple unified picture of the incoherent nonlinear optical properties of different types of photofunctional materials.
基于逐步双光子吸收（2PA）过程的非相干非线性光物理和光化学过程，由于其具有超越单光子过程的独特光响应以及比相干非线性光学过程更低的诱导过程功率阈值，近年来已在材料科学中得到应用。其中，非线性光致变色材料受到了广泛关注，因为与其他非相干非线性过程相比，它们表现出非常规的光响应，例如单分子系统的低功率阈值非线性光响应、门控光化学反应和对氧不敏感的非线性光响应。非线性光致变色材料不仅对于比色材料很重要，而且对于能够丰富下一代社会的新兴材料，如有望用于三维显示的动态全息材料也很重要。在本教程综述中，我们介绍了使用逐步2PA过程的低功率阈值非线性光致变色材料。首先，我们解释光化学以及光致变色反应的基本概念。我们试图利用这些基本概念对非相干非线性光学过程提供直观的理解。然后，我们介绍非线性光致变色材料的几个最新实例和潜在应用。本教程综述对于理解与这些领域相关的科学进展很重要，并提供了不同类型光功能材料非相干非线性光学性质的简单统一图景。
